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138-794: The Mack AC was a heavy cargo truck designed in the 1910s by the American manufacturer Mack Trucks . Introduced in 1916, the Mack AC saw extensive service during the First World War with the British and American armed forces, in British service it was given the nickname the "Bulldog" which led to Mack adopting the Bulldog as its corporate symbol. Mack introduced the AC model in 1916 to replace their Mack Senior model which dated from 1905. Mack's chief engineer, Edward Hewitt,
276-406: A fifth wheel hitch. Box trucks have walls and a roof, making an enclosed load space. The rear has doors for unloading; a side door is sometimes fitted. Chassis cab trucks have a fully enclosed cab at the front, with bare chassis frame-rails behind, suitable for subsequent permanent attachment of a specialized payload, like a fire-truck or ambulance body. Concrete mixers have
414-557: A $ 3,000-per-day fine to be assessed for any delay. To meet the deadline, Six Companies had to complete work by early 1933, since only in late fall and winter was the water level in the river low enough to safely divert. Tunneling began at the lower portals of the Nevada tunnels in May 1931. Shortly afterward, work began on two similar tunnels in the Arizona canyon wall. In March 1932, work began on lining
552-482: A 40-foot (12 m) rock dam which could generate 10,000 horsepower (7,500 kW). However, at the time , the limit of transmission of electric power was 80 miles (130 km), and there were few customers (mostly mines) within that limit. Edison allowed land options it held on the river to lapse—including an option for what became the site of Hoover Dam. In the following years, the Bureau of Reclamation (BOR), known as
690-464: A body variation of a neighborhood electric vehicle . A few manufactures produce specialized chassis for this type of vehicle, while Zap Motors markets a version of their Xebra electric tricycle (licensable in the U.S. as a motorcycle). Popular in Europe and Asia, many mini-trucks are factory redesigns of light automobiles, usually with monocoque bodies. Specialized designs with substantial frames such as
828-524: A chain drive A 1903 Eldridge truck is displayed at the Iowa 80 Trucking Museum, Walcott, Iowa. Trucks of the era mostly used two-cylinder engines and had a carrying capacity of 1.5 to 2 t (3,300 to 4,400 lb). After World War I, several advances were made: electric starters , and 4, 6, and 8 cylinder engines. Although it had been invented in 1897, the diesel engine did not appear in production trucks until Benz introduced it in 1923. The diesel engine
966-506: A common ancestor: the steam-powered fardier Nicolas-Joseph Cugnot built in 1769. However, steam wagons were not common until the mid-19th century. The roads of the time, built for horse and carriages, limited these vehicles to very short hauls, usually from a factory to the nearest railway station. The first semi-trailer appeared in 1881, towed by a steam tractor manufactured by De Dion-Bouton . Steam-powered wagons were sold in France and
1104-401: A common construction: they are made of a chassis , a cab , an area for placing cargo or equipment, axles , suspension and roadwheels , an engine and a drivetrain . Pneumatic , hydraulic , water , and electrical systems may also be present. Many also tow one or more trailers or semi-trailers. The "cab", or "cabin" is an enclosed space where the driver is seated. A " sleeper " is
1242-704: A compartment attached to or integral with the cab where the driver can rest while not driving, sometimes seen in semi-trailer trucks. There are several cab configurations: A further step from this is the side loading forklift that can be described as a specially fabricated vehicle with the same properties as a truck of this type, in addition to the ability to pick up its own load. Most small trucks such as sport utility vehicles (SUVs), vans or pickups , and even light medium-duty trucks in North America, China, and Russia use gasoline engines (petrol engines), but many diesel engined models are now being produced. Most of
1380-705: A desolate area Beatty named the Imperial Valley . Though water from the Alamo Canal allowed for the widespread settlement of the valley, the canal proved expensive to operate. After a catastrophic breach that caused the Colorado River to fill the Salton Sea , the Southern Pacific Railroad spent $ 3 million in 1906–07 to stabilize the waterway, an amount it hoped in vain that it would be reimbursed for by
1518-491: A flash flood while looking for an ideal spot for the dam was the second person. The official list's final death occurred on December 20, 1935, when Patrick Tierney, electrician's helper and the son of J.G. Tierney, fell from one of the two Arizona-side intake towers. Included in the fatality list are three workers who took their own lives on site, one in 1932 and two in 1933. Of the 112 fatalities, 91 were Six Companies employees, three were Bureau of Reclamation employees, and one
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#17328633543661656-449: A form by only 1 inch (25 mm), and Six Companies engineers would not have permitted a flaw caused by the presence of a human body. A total of 3,250,000 cubic yards (2,480,000 cubic meters) of concrete was used in the dam before concrete pouring ceased on May 29, 1935. In addition, 1,110,000 cu yd (850,000 m ) were used in the power plant and other works. More than 582 miles (937 km) of cooling pipes were placed within
1794-406: A ladder if tipped on end. The rails consist of a tall vertical section (two if boxed) and two shorter horizontal flanges. The height of the vertical section provides opposition to vertical flex when weight is applied to the top of the frame (beam resistance). Though typically flat the whole length on heavy-duty trucks, the rails may sometimes be tapered or arched for clearance around the engine or over
1932-420: A manual transmission with synchromesh (synchronizers). Bigger trucks often use manual transmissions without synchronizers, saving bulk and weight, although synchromesh transmissions are used in larger trucks as well. Transmissions without synchronizers, known as "crash boxes", require double-clutching for each shift, (which can lead to repetitive motion injuries), or a technique known colloquially as "floating",
2070-545: A manual transmission, while conventional automatic or automated manual transmissions would have anything from 5 to 12 gears. Almost all heavy truck transmissions are of the "range and split" (double H shift pattern) type, where range change and so‑called half gears or splits are air operated and always preselected before the main gear selection. A truck frame consists of two parallel boxed (tubular) or C‑shaped rails, or beams, held together by crossmembers . These frames are referred to as ladder frames due to their resemblance to
2208-407: A method of changing gears which does not use the clutch, except for starts and stops, due to the physical effort of double-clutching, especially with non-power-assisted clutches, faster shifts, and less clutch wear. Double-clutching allows the driver to control the engine and transmission revolutions to synchronize so that a smooth shift can be made; for example, when upshifting, the accelerator pedal
2346-588: A new record low elevation of 1,071.61 feet (326.63 m) on July 1, 2016, before beginning to rebound slowly. Under its original design, the dam would no longer be able to generate power once the water level fell below 1,050 feet (320 m), which might have occurred in 2017 had water restrictions not been enforced. To lower the minimum power pool elevation from 1,050 to 950 feet (320 to 290 m), five wide-head turbines, designed to work efficiently with less flow, were installed. Water levels were maintained at over 1,075 feet (328 m) in 2018 and 2019, but fell to
2484-443: A new record low of 1,071.55 feet (326.61 m) on June 10, 2021 and were projected to fall below 1,066 feet (325 m) by the end of 2021. Control of water was the primary concern in the building of the dam. Power generation has allowed the dam project to be self-sustaining: proceeds from the sale of power repaid the 50-year construction loan, and those revenues also finance the multimillion-dollar yearly maintenance budget. Power
2622-406: A popular choice for fire engines , in both rigid and articulated forms. Truck A truck or lorry is a motor vehicle designed to transport freight , carry specialized payloads, or perform other utilitarian work. Trucks vary greatly in size, power, and configuration, but the vast majority feature body-on-frame construction, with a cabin that is independent of the payload portion of
2760-413: A pumping station 20 miles (32 km) downriver. Electricity from the dam's powerhouse was originally sold pursuant to a fifty-year contract, authorized by Congress in 1934, which ran from 1937 to 1987. In 1984, Congress passed a new statute which set power allocations to southern California, Arizona, and Nevada from the dam from 1987 to 2017. The powerhouse was run under the original authorization by
2898-401: A roof and floor, used for transporting fresh and frozen cargo such as ice cream, food, vegetables, and prescription drugs. They are mostly equipped with double-wing rear doors, but a side door is sometimes fitted. Refuse trucks have a specialized body for collecting and, often, compacting trash collected from municipal, commercial, and industrial sites. This application has the widest use of
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#17328633543663036-544: A rotating drum on an inclined axis, rotating in one direction to mix, and in the other to discharge the concrete down chutes. Because of the weight and power requirements of the drum body and rough construction sites, mixers have to be very heavy duty. Dual drive/Steer trucks are vehicles used to steer the rear of trailers . Dump trucks ("tippers" in the UK) transport loose material such as sand, gravel, or dirt for construction. A typical dump truck has an open-box bed, which
3174-493: A set of 1-inch (25 mm) steel pipes; cool river water would be poured through the pipes, followed by ice-cold water from a refrigeration plant. When an individual block had cured and had stopped contracting, the pipes were filled with grout . Grout was also used to fill the hairline spaces between columns, which were grooved to increase the strength of the joints. The concrete was delivered in huge steel buckets 7 feet high (2.1 m) and almost 7 feet in diameter; Crowe
3312-704: A six-axle truck may have a maximum weight of 44 t (97,000 lb) or more. Off-road trucks include standard, extra heavy-duty highway-legal trucks, typically outfitted with off-road features such as a front driving axle and special tires for applications such as logging and construction, and purpose-built off-road vehicles unconstrained by weight limits, such as the Liebherr T 282B mining truck. Australia has complex regulations over weight and length, including axle spacing, type of axle/axle group, rear overhang, kingpin to rear of trailer, drawbar length, ground clearance, as well as height and width laws. These limits are some of
3450-497: A total of 40,299 produced, along with 2,819 AKs and 285 APs. The AC was widely used in construction and road-building, with many used in the construction of the Hoover Dam . The AC was among the strongest trucks ever made, and solid-tire ACs built in the 1920s were still a common sight in American cities in the 1950s, and not unknown in the 1960s. The AC's chassis, along with that of the AP, was
3588-677: A trailer is not a truck but a " tractor ". The majority of trucks currently in use are powered by diesel engines , although small- to medium-size trucks with gasoline engines exist in North America . Electrically powered trucks are more popular in China and Europe than elsewhere. In the European Union , vehicles with a gross combination mass of up to 3.5 t (3.4 long tons; 3.9 short tons) are defined as light commercial vehicles , and those over as large goods vehicles . Trucks and cars have
3726-411: A truck, of a trailer, from axle to hitch point, kingpin to rear of trailer, and turning radius are all regulated. In additions, there are special rules for carrying containers, and countries can set their own rules for local traffic. The United States Federal Bridge Law deals with the relation between the gross weight of the truck, the number of axles, the weight on and the spacing between the axles that
3864-647: Is called a bakkie ( Afrikaans : "small open container"). In the United Kingdom, India, Malaysia, Singapore, Ireland, and Hong Kong lorry is used instead of truck , but only for the medium and heavy types, while truck is used almost exclusively to refer to pickups . Often produced as variations of golf cars , with internal combustion or battery electric drive , these are used typically for off-highway use on estates, golf courses, and parks. While not suitable for highway use some variations may be licensed as slow speed vehicles for operation on streets, generally as
4002-516: Is credited with designing the AC which on its introduction was so innovative it had 18 patents on various aspects of its design. When introduced, the AC complimented the smaller AB, another Hewitt design, that was introduced in 1914 to replace Mack's older Junior model. The AC was a two-wheel drive , two-axle truck which was made in three sizes, with payloads of 3 + 1 ⁄ 2 long tons (3.6 t), 5 + 1 ⁄ 2 long tons (5.6 t) and 7 + 1 ⁄ 2 long tons (7.6 t). The AC
4140-512: Is generated in step with and only with the release of water in response to downstream water demands. Lake Mead and downstream releases from the dam also provide water for both municipal and irrigation uses. Water released from the Hoover Dam eventually reaches several canals. The Colorado River Aqueduct and Central Arizona Project branch off Lake Havasu while the All-American Canal
4278-427: Is hinged at the rear and lifts at the front, allowing the material in the bed to be unloaded ("dumped") on the ground behind the truck. Flatbed trucks have an entirely flat, level platform body. This allows for quick and easy loading but has no protection for the load. Hanging or removable sides are sometimes fitted, often in the form of a stakebody . Refrigerator trucks have insulated panels as walls and
Mack AC - Misplaced Pages Continue
4416-422: Is in neutral, it allows the engine speed to drop and synchronize engine and transmission revolutions relative to the road speed. Downshifting is performed in a similar fashion, except the engine speed is now required to increase (while the transmission is in neutral) just the right amount in order to achieve the synchronization for a smooth, non-collision gear change. "Skip changing" is also widely used; in principle,
4554-416: Is located near Boulder City, Nevada , a municipality originally constructed for workers on the construction project, about 30 mi (48 km) southeast of Las Vegas , Nevada. The dam's generators provide power for public and private utilities in Nevada, Arizona, and California. Hoover Dam is a major tourist attraction, with 7 million tourists a year. The heavily traveled U.S. Route 93 (US 93) ran along
4692-564: Is most often made as vans. Medium trucks are larger than light but smaller than heavy trucks. In the US, they are defined as weighing between 13,000 and 33,000 lb (5.9 and 15.0 t). For the UK and the EU the weight is between 3.5 and 7.5 t (7,700 and 16,500 lb). Local delivery and public service ( dump trucks , garbage trucks and fire-fighting trucks ) are normally around this size. Heavy trucks are
4830-448: Is not subject to alkali–silica reaction (ASR), as the Hoover Dam builders happened to use nonreactive aggregate, unlike that at downstream Parker Dam , where ASR has caused measurable deterioration. With most work finished on the dam itself (the powerhouse remained uncompleted), a formal dedication ceremony was arranged for September 30, 1935, to coincide with a western tour being made by President Franklin D. Roosevelt . The morning of
4968-412: Is released and the clutch pedal is depressed while the gear lever is moved into neutral, the clutch pedal is then released and quickly pushed down again while the gear lever is moved to the next higher gear. Finally, the clutch pedal is released and the accelerator pedal pushed down to obtain the required engine speed. Although this is a relatively fast movement, perhaps a second or so while the transmission
5106-559: Is supplied by the Imperial Dam . In total, water from Lake Mead serves 18 million people in Arizona, Nevada, and California and supplies the irrigation of over 1,000,000 acres (400,000 ha) of land. In 2018, the Los Angeles Department of Water and Power (LADWP) proposed a $ 3 billion pumped-storage hydroelectricity project—a "battery" of sorts—that would use wind and solar power to recirculate water back up to Lake Mead from
5244-534: The Daimler Motor Lastwagen . Other companies, such as Peugeot , Renault and Büssing , also built their own versions. The first truck in the United States was built by Autocar in 1899 and was available with 5 or 8 horsepower (4 or 6 kW) engines. Another early American truck was built by George Eldridge of Des Moines, Iowa, in 1903. It was powered by an engine with two opposed cylinders, and had
5382-526: The Parker , Shasta and Grand Coulee dams and power plants. True's work on the Hoover Dam was humorously referred to in a poem published in The New Yorker , part of which read, "lose the spark, and justify the dream; but also worthy of remark will be the color scheme". Complementing Kaufmann and True's work, sculptor Oskar J. W. Hansen designed many of the sculptures on and around the dam. His works include
5520-523: The cab-over configuration in North America, to provide better maneuverability in tight situations. They are also among the most severe-duty and highest GVWR trucks on public roads. Semi-tractors ("artics" in the UK) have a fifth wheel for towing a semi-trailer instead of a body. Hoover Dam Hoover Dam is a concrete arch-gravity dam in the Black Canyon of the Colorado River , on
5658-461: The phase-out of fossil fuel vehicles includes trucks. According to The Economist magazine "Electric lorries will probably run on hydrogen, not batteries, which are too expensive." Other researchers say that once faster chargers are available batteries will become competitive against diesel for all, except perhaps the heaviest, trucks. Small trucks use the same type of transmissions as almost all cars, having either an automatic transmission or
Mack AC - Misplaced Pages Continue
5796-530: The rail transport industry, where the word is known to have been used in 1838 to refer to a type of truck (a goods wagon as in British usage, not a bogie as in the American), specifically a large flat wagon. It might derive from the verb lurry (to carry or drag along, or to lug) which was in use as early as 1664, but that association is not definitive. The expanded meaning of lorry , "self-propelled vehicle for carrying goods", has been in usage since 1911. In
5934-407: The "Wobblies", they formed a committee to represent them with the company. The committee drew up a list of demands that evening and presented them to Crowe the following morning. He was noncommittal. The workers hoped that Crowe, the general superintendent of the job, would be sympathetic; instead, he gave a scathing interview to a newspaper, describing the workers as "malcontents". On the morning of
6072-544: The 2000s when new chemistries and higher-volume production broadened the range of applicability of electric propulsion to trucks in many more roles. Today, manufacturers are electrifying all trucks ahead of national regulatory requirements, with long-range over-the-road trucks being the most challenging. Truck is used in American English ; the British English equivalent is lorry. The first known usage of "truck"
6210-418: The 9th, Crowe met with the committee and told them that management refused their demands, was stopping all work, and was laying off the entire work force, except for a few office workers and carpenters. The workers were given until 5 p.m. to vacate the premises. Concerned that a violent confrontation was imminent, most workers took their paychecks and left for Las Vegas to await developments. Two days later,
6348-463: The AC was its hood and dashboard mounted radiator (mounted behind the engine) which was covered by a squared off bonnet of a coal scuttle pattern which had a small circular grille at the front containing the Mack emblem, all of which gave the model its distinctive appearance. The AC's pressed chrome-nickel steel chassis was heat-treated for durability. Chain drive was used to drive the rear wheels while
6486-595: The Colorado River as a federal concern because the river's basin covered several states, and the river eventually entered Mexico. Though the Fall-Davis report called for a dam "at or near Boulder Canyon", the Reclamation Service (which was renamed the Bureau of Reclamation the following year) found that canyon unsuitable. One potential site at Boulder Canyon was bisected by a geologic fault ; two others were so narrow there
6624-433: The Colorado River usually passes through the turbines. The spillways and outlet works (jet-flow gates) are rarely used. The jet-flow gates, located in concrete structures 180 feet (55 m) above the river and also at the outlets of the inner diversion tunnels at river level, may be used to divert water around the dam in emergency or flood conditions, but have never done so, and in practice are used only to drain water from
6762-526: The Italian Piaggio shown here are based upon Japanese designs (in this case by Daihatsu ) and are popular for use in "old town" sections of European cities that often have very narrow alleyways. Regardless of name, these small trucks serve a wide range of uses. In Japan, they are regulated under the Kei car laws, which allow vehicle owners a break in taxes for buying a smaller and less-powerful vehicle (currently,
6900-491: The Los Angeles Department of Water and Power and Southern California Edison; in 1987, the Bureau of Reclamation assumed control. In 2011, Congress enacted legislation extending the current contracts until 2067, after setting aside 5% of Hoover Dam's power for sale to Native American tribes, electric cooperatives, and other entities. The new arrangement began on October 1, 2017. The Bureau of Reclamation reports that
7038-569: The President's speech, in which he avoided mentioning the name of former President Hoover, who was not invited to the ceremony. To mark the occasion, a three-cent stamp was issued by the United States Post Office Department —bearing the name "Boulder Dam", the official name of the dam between 1933 and 1947. After the ceremony, Roosevelt made the first visit by any American president to Las Vegas. Most work had been completed by
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#17328633543667176-490: The Reclamation Service at the time, also considered the Lower Colorado as the site for a dam. Service chief Arthur Powell Davis proposed using dynamite to collapse the walls of Boulder Canyon, 20 miles (32 km) north of the eventual dam site, into the river. The river would carry off the smaller pieces of debris, and a dam would be built incorporating the remaining rubble. In 1922, after considering it for several years,
7314-476: The Reclamation Service finally rejected the proposal, citing doubts about the unproven technique and questions as to whether it would, in fact, save money. In 1922, the Reclamation Service presented a report calling for the development of a dam on the Colorado River for flood control and electric power generation. The report was principally authored by Davis and was called the Fall-Davis report after Interior Secretary Albert Fall . The Fall-Davis report cited use of
7452-586: The Republic , were both formed in a continuous pour. To put such large bronzes into place without marring the highly polished bronze surface, they were placed on ice and guided into position as the ice melted. Hansen's bas-relief on the Nevada elevator tower depicts the benefits of the dam: flood control, navigation, irrigation, water storage, and power. The bas-relief on the Arizona elevator depicts, in his words, "the visages of those Indian tribes who have inhabited mountains and plains from ages distant." Excavation for
7590-483: The Salton Sea. The Board cautioned: "To avoid such possibilities, the proposed dam should be constructed on conservative if not ultra-conservative lines." On December 21, 1928, President Coolidge signed the bill authorizing the dam. The Boulder Canyon Project Act appropriated $ 165 million for the project along with the downstream Imperial Dam and All-American Canal , a replacement for Beatty's canal entirely on
7728-522: The Supreme Court handed down the Wyoming v. Colorado decision undermining the claims of the upstream states, they became anxious to reach an agreement. The resulting Colorado River Compact was signed on November 24, 1922. Legislation to authorize the dam was introduced repeatedly by two California Republicans, Representative Phil Swing and Senator Hiram Johnson , but representatives from other parts of
7866-497: The U.S. side of the border. It also permitted the compact to go into effect when at least six of the seven states approved it. This occurred on March 6, 1929, with Utah's ratification; Arizona did not approve it until 1944. Even before Congress approved the Boulder Canyon Project, the Bureau of Reclamation was considering what kind of dam should be used. Officials eventually decided on a massive concrete arch-gravity dam ,
8004-400: The US government who adopted it as a standard type, using 3 1 ⁄ 2 , 5 1 ⁄ 2 and 7 1 ⁄ 2 ton versions. Additionally, approximately 2,000 ACs were delivered to the British military during the war. It proved to be extremely popular in British service with British troops appreciating the AC's tough characteristics and reliability; the AC had a reputation for withstanding
8142-535: The US, no more than 13,900 lb (6.3 t)) and are used by individuals and businesses alike. In the EU they may not weigh more than 3.5 t (7,700 lb) and are allowed to be driven with a driving licence for cars. Pickup trucks , called utes in Australia and New Zealand, are common in North America and some regions of Latin America, Asia, and Africa, but not so in Europe, where this size of commercial vehicle
8280-429: The United States until the eve of World War I , and 1935 in the United Kingdom, when a change in road tax rules made them uneconomic against the new diesel lorries. In 1895, Karl Benz designed and built the first internal combustion truck. Later that year some of Benz's trucks were modified to become busses by Netphener . A year later, in 1896, another internal combustion engine truck was built by Gottlieb Daimler ,
8418-556: The United States, Canada, and the Philippines, "truck" is usually reserved for commercial vehicles larger than regular passenger cars, but includes large SUVs, pickups, and other vehicles with an open load bed. In Australia, New Zealand and South Africa, the word "truck" is mostly reserved for larger vehicles. In Australia and New Zealand, a pickup truck is frequently called a ute (short for "utility" vehicle), while in South Africa it
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#17328633543668556-546: The World (IWW or "Wobblies"), though much-reduced from their heyday as militant labor organizers in the early years of the century, hoped to unionize the Six Companies workers by capitalizing on their discontent. They sent eleven organizers, several of whom were arrested by Las Vegas police. On August 7, 1931, the company cut wages for all tunnel workers. Although the workers sent the organizers away, not wanting to be associated with
8694-476: The arch-gravity as was proposed for the Black Canyon dam, opponents claimed that the Black Canyon dam's safety could not be guaranteed. Congress authorized a board of engineers to review plans for the proposed dam. The Colorado River Board found the project feasible, but warned that should the dam fail, every downstream Colorado River community would be destroyed, and that the river might change course and empty into
8832-547: The assistance of the National Laboratory of Anthropology, True researched authentic decorative motifs from Indian sand paintings, textiles, baskets and ceramics. The images and colors are based on Native American visions of rain, lightning, water, clouds, and local animals—lizards, serpents, birds—and on the Southwestern landscape of stepped mesas. In these works, which are integrated into the walkways and interior halls of
8970-403: The axles. The holes in rails are used either for mounting vehicle components and running wires and hoses or measuring and adjusting the orientation of the rails at the factory or repair shop. The frame is usually made of steel , but can be made (whole or in part) of aluminum for a lighter weight. A tow bar may be found attached at one or both ends, but heavy tractors almost always make use of
9108-416: The bid documents in nearly as much detail as the dam itself. The upper cofferdam was 96 ft (29 m) high, and 750 feet (230 m) thick at its base, thicker than the dam itself. It contained 650,000 cubic yards (500,000 m ) of material. When the cofferdams were in place and the construction site was drained of water, excavation for the dam foundation began. For the dam to rest on solid rock, it
9246-501: The border between the U.S. states of Nevada and Arizona . Constructed between 1931 and 1936, during the Great Depression , it was dedicated on September 30, 1935, by President Franklin D. Roosevelt . Its construction was the result of a massive effort involving thousands of workers, and cost over 100 lives. In bills passed by Congress during its construction, it was referred to as the Hoover Dam, after President Herbert Hoover , but
9384-461: The bottom, narrowing to 45 ft (14 m) at the top, leaving room for a highway connecting Nevada and Arizona. On January 10, 1931, the Bureau made the bid documents available to interested parties, at five dollars a copy. The government was to provide the materials, and the contractor was to prepare the site and build the dam. The dam was described in minute detail, covering 100 pages of text and 76 drawings. A $ 2 million bid bond
9522-461: The bypass tunnels, as the tunnel had to be used to take in irrigation water until the powerhouse went into operation. There were 112 deaths reported as associated with the construction of the dam. The first was Bureau of Reclamation employee Harold Connelly who died on May 15, 1921, after falling from a barge while surveying the Colorado River for an ideal spot for the dam. Surveyor John Gregory ("J.G.") Tierney, who drowned on December 20, 1922, in
9660-568: The canyon wall, to house 480 single men at what became known as River Camp. Workers with families were left to provide their own accommodations until Boulder City could be completed, and many lived in Ragtown. The site of Hoover Dam endures extremely hot weather, and the summer of 1931 was especially torrid, with the daytime high averaging 119.9 °F (48.8 °C). Sixteen workers and other riverbank residents died of heat prostration between June 25 and July 26, 1931. The Industrial Workers of
9798-486: The clocks display the same time for more than half the year. At Kaufmann's request, Denver artist Allen Tupper True was hired to handle the design and decoration of the walls and floors of the new dam. True's design scheme incorporated motifs of the Navajo and Pueblo tribes of the region. Although some were initially opposed to these designs, True was given the go-ahead and was officially appointed consulting artist. With
9936-419: The concrete. Overall, there is enough concrete in the dam to pave a two-lane highway from San Francisco to New York. Concrete cores were removed from the dam for testing in 1995; they showed that "Hoover Dam's concrete has continued to slowly gain strength" and the dam is composed of a "durable concrete having a compressive strength exceeding the range typically found in normal mass concrete". Hoover Dam concrete
10074-481: The construction period. The initial plans for the facade of the dam, the power plant, the outlet tunnels and ornaments clashed with the modern look of an arch dam. The Bureau of Reclamation, more concerned with the dam's functionality, adorned it with a Gothic -inspired balustrade and eagle statues. This initial design was criticized by many as being too plain and unremarkable for a project of such immense scale, so Los Angeles-based architect Gordon B. Kaufmann , then
10212-482: The country considered the project as hugely expensive and one that would mostly benefit California. The 1927 Mississippi flood made Midwestern and Southern congressmen and senators more sympathetic toward the dam project. On March 12, 1928, the failure of the St. Francis Dam , constructed by the city of Los Angeles, caused a disastrous flood that killed up to 600 people. As that dam was a curved-gravity type, similar in design to
10350-408: The dam (from pea-sized gravel to 9 inches [230 mm] stones), it was vital that the bucket be maneuvered to the proper column. When the bottom of the bucket opened up, disgorging 8 cu yd (6.1 m ) of concrete, a team of men worked it throughout the form. Although there are myths that men were caught in the pour and are entombed in the dam to this day, each bucket deepened the concrete in
10488-550: The dam could be built, the Colorado River needed to be diverted away from the construction site. To accomplish this, four diversion tunnels were driven through the canyon walls, two on the Nevada side and two on the Arizona side. These tunnels were 56 ft (17 m) in diameter. Their combined length was nearly 16,000 ft, or more than 3 miles (5 km). The contract required these tunnels to be completed by October 1, 1933, with
10626-617: The dam feared endless litigation. Delph Carpenter, a Colorado attorney, proposed that the seven states which fell within the river's basin (California, Nevada, Arizona, Utah, New Mexico, Colorado and Wyoming) form an interstate compact , with the approval of Congress. Such compacts were authorized by Article I of the United States Constitution but had never been concluded among more than two states. In 1922, representatives of seven states met with then- Secretary of Commerce Herbert Hoover . Initial talks produced no result, but when
10764-399: The dam site was reinforced with grout , forming a grout curtain . Holes were driven into the walls and base of the canyon, as deep as 150 feet (46 m) into the rock, and any cavities encountered were to be filled with grout. This was done to stabilize the rock, to prevent water from seeping past the dam through the canyon rock, and to limit "uplift"—upward pressure from water seeping under
10902-400: The dam was authorized, increasing numbers of unemployed people converged on southern Nevada. Las Vegas, then a small city of some 5,000, saw between 10,000 and 20,000 unemployed descend on it. A government camp was established for surveyors and other personnel near the dam site; this soon became surrounded by a squatters' camp. Known as McKeeversville, the camp was home to men hoping for work on
11040-461: The dam wound down. When a Six Companies manager altered working times to force workers to take lunch on their own time, workers responded with a strike. Emboldened by Crowe's reversal of the lunch decree, workers raised their demands to include a $ 1-per-day raise. The company agreed to ask the Federal government to supplement the pay, but no money was forthcoming from Washington. The strike ended. Before
11178-640: The dam's crest until October 2010, when the Hoover Dam Bypass opened. As the United States developed the Southwest, the Colorado River was seen as a potential source of irrigation water. An initial attempt at diverting the river for irrigation purposes occurred in the late 1890s, when land speculator William Beatty built the Alamo Canal just north of the Mexican border; the canal dipped into Mexico before running to
11316-444: The dam's total power output was placed on the grid and made arbitrarily distributable. Before water from Lake Mead reaches the turbines, it enters the intake towers and then four gradually narrowing penstocks which funnel the water down towards the powerhouse. The intakes provide a maximum hydraulic head (water pressure) of 590 ft (180 m) as the water reaches a speed of about 85 mph (140 km/h). The entire flow of
11454-405: The dam, True also reflected on the machinery of the operation, making the symbolic patterns appear both ancient and modern. With the agreement of Kaufmann and the engineers, True also devised for the pipes and machinery an innovative color-coding which was implemented throughout all BOR projects. True's consulting artist job lasted through 1942; it was extended so he could complete design work for
11592-409: The dam. The workers were under severe time constraints due to the beginning of the concrete pour. When they encountered hot springs or cavities too large to readily fill, they moved on without resolving the problem. A total of 58 of the 393 holes were incompletely filled. After the dam was completed and the lake began to fill, large numbers of significant leaks caused the Bureau of Reclamation to examine
11730-559: The daring." Hansen's dedication plaza, on the Nevada abutment, contains a sculpture of two winged figures flanking a flagpole. Surrounding the base of the monument is a terrazzo floor embedded with a "star map". The map depicts the Northern Hemisphere sky at the moment of President Roosevelt's dedication of the dam. This is intended to help future astronomers, if necessary, calculate the exact date of dedication. The 30-foot-high (9.1 m) bronze figures, dubbed Winged Figures of
11868-467: The dedication, and Six Companies negotiated with the government through late 1935 and early 1936 to settle all claims and arrange for the formal transfer of the dam to the Federal Government. The parties came to an agreement and on March 1, 1936, Secretary Ickes formally accepted the dam on behalf of the government. Six Companies was not required to complete work on one item, a concrete plug for one of
12006-513: The dedication, it was moved forward three hours from 2 p.m. Pacific time to 11 a.m.; this was done because Secretary of the Interior Harold L. Ickes had reserved a radio slot for the President for 2 p.m. but officials did not realize until the day of the ceremony that the slot was for 2 p.m. Eastern Time. Despite the change in the ceremony time, and temperatures of 102 °F (39 °C), 10,000 people were present for
12144-411: The design of which was overseen by the Bureau's chief design engineer John L. Savage . The monolithic dam would be thick at the bottom and thin near the top and would present a convex face towards the water above the dam. The curving arch of the dam would transmit the water's force into the abutments, in this case the rock walls of the canyon. The wedge-shaped dam would be 660 ft (200 m) thick at
12282-535: The diversion tunnels), and a classification used by Six Companies to avoid paying compensation claims. The site's diversion tunnels frequently reached 140 °F (60 °C), enveloped in thick plumes of vehicle exhaust gases. A total of 42 workers were recorded as having died from pneumonia and were not included in the above total; none were listed as having died from carbon monoxide poisoning. No deaths of non-workers from pneumonia were recorded in Boulder City during
12420-590: The energy generated under the contracts ending in 2017 was allocated as follows: The dam is protected against over-topping by two spillways . The spillway entrances are located behind each dam abutment , running roughly parallel to the canyon walls. The spillway entrance arrangement forms a classic side-flow weir with each spillway containing four 100-foot-long (30 m) and 16-foot-wide (4.9 m) steel-drum gates. Each gate weighs 5,000,000 pounds (2,300 metric tons) and can be operated manually or automatically. Gates are raised and lowered depending on water levels in
12558-827: The engine is limited to 660 cc displacement). These vehicles are used as on-road utility vehicles in Japan. These Japanese-made mini-trucks that were manufactured for on-road use are competing with off-road ATVs in the United States, and import regulations require that these mini-trucks have a 25 mph (40 km/h) speed governor as they are classified as low-speed vehicles. These vehicles have found uses in construction, large campuses (government, university, and industrial), agriculture, cattle ranches, amusement parks, and replacements for golf carts. Major mini-truck manufacturers and their brands include: Daihatsu Hijet , Honda Acty , Tata Ace , Mazda Scrum , Mitsubishi Minicab , Subaru Sambar , and Suzuki Carry . Light trucks are car-sized (in
12696-527: The federal government. Even after the waterway was stabilized, it proved unsatisfactory because of constant disputes with landowners on the Mexican side of the border. As the technology of electric power transmission improved, the Lower Colorado was considered for its hydroelectric -power potential. In 1902, the Edison Electric Company of Los Angeles surveyed the river in the hope of building
12834-415: The first three Allis Chalmers built Francis turbine - generators , all on the Nevada side, began operating. In March 1937, one more Nevada generator went online and the first Arizona generator by August. By September 1939, four more generators were operating, and the dam's power plant became the largest hydroelectricity facility in the world. The final generator was not placed in service until 1961, bringing
12972-443: The front axle was made of drop-forged alloy steel for extra strength. Like most heavy trucks of the era, the AC used solid tires initially, although towards the end of its production run many were delivered with pneumatic tires . The AC had an all-steel cab with an optional metal roof. One innovation introduced in the AC was the positioning of the steering wheel at a 45-degree angle which greatly improved driver comfort. The Mack AK
13110-525: The headquarters for the dam construction, closing its many speakeasies when the decision maker, Secretary of the Interior Ray Wilbur , came to town. Instead, Wilbur announced in early 1930 that a model city was to be built in the desert near the dam site. This town became known as Boulder City, Nevada . Construction of a rail line joining Las Vegas and the dam site began in September 1930. Soon after
13248-443: The heavier trucks use four-stroke diesel engines with a turbocharger and intercooler . Huge off-highway trucks use locomotive-type engines such as a V12 Detroit Diesel two stroke engine. A large proportion of refuse trucks in the United States employ CNG (compressed natural gas) engines for their low fuel cost and reduced carbon emissions. A significant proportion of North American manufactured trucks use an engine built by
13386-440: The highest in the world, a B-double can weigh 62.5 t (61.5 long tons; 68.9 short tons) and be 25 m (82 ft) long, and road trains used in the outback can weigh 172 t (169.3 long tons; 189.6 short tons) and be 53.5 m (176 ft) long. The European Union also has complex regulations. The number and spacing of axles, steering, single or dual tires, and suspension type all affect maximum weights. Length of
13524-407: The largest on-road trucks, Class 8 . These include vocational applications such as heavy dump trucks, concrete pump trucks, and refuse hauling, as well as ubiquitous long-haul 4x2 and 6×4 tractor units . Road damage and wear increase very rapidly with the axle weight. The number of steering axles and the suspension type also influence the amount of the road wear. In many countries with good roads
13662-514: The last remaining major independent engine manufacturer ( Cummins ) but most global OEMs such as Volvo Trucks and Daimler AG promote their own "captive" engines. In the European Union, all new truck engines must comply with Euro VI emission regulations, and Euro 7 from the late 2020s has stricter exhaust limits and also limits air pollution from brakes and tires . As of 2019 several alternative technologies are competing to displace
13800-409: The maximum generating capacity to 1,345 megawatts at the time. Original plans called for 16 large generators, eight on each side of the river, but two smaller generators were installed instead of one large one on the Arizona side for a total of 17. The smaller generators were used to serve smaller communities at a time when the output of each generator was dedicated to a single municipality, before
13938-472: The mid-19th-century. In the 1920s Autocar Trucks was the first of the major truck manufacturers to offer a range of electric trucks for sale. Electric trucks were successful for urban delivery roles and as specialized work vehicles like forklifts and pushback tugs . The higher energy density of liquid fuels soon led to the decline of electric-powered trucks in favor of, first, gasoline, and then diesel and CNG-fueled engines until battery technology advanced in
14076-400: The monument of dedication plaza, a plaque to memorialize the workers killed and the bas-reliefs on the elevator towers. In his words, Hansen wanted his work to express "the immutable calm of intellectual resolution, and the enormous power of trained physical strength, equally enthroned in placid triumph of scientific accomplishment", because "[t]he building of Hoover Dam belongs to the sagas of
14214-473: The most common cause of death on the dam site; the high scalers' work thus helped ensure worker safety. One high scaler was able to save a life in a more direct manner: when a government inspector lost his grip on a safety line and began tumbling down a slope towards almost certain death, a high scaler was able to intercept him and pull him into the air. The construction site had become a magnet for tourists. The high scalers were prime attractions and showed off for
14352-512: The name. The name was descriptive and was an inside joke among the San Franciscans in the bid, where "Six Companies" was also a Chinese benevolent association in the city . There were three valid bids, and Six Companies' bid of $ 48,890,955 was the lowest, within $ 24,000 of the confidential government estimate of what the dam would cost to build, and five million dollars less than the next-lowest bid. The city of Las Vegas had lobbied hard to be
14490-432: The nation's leading dam builder, Frank Crowe . They formed a joint venture to bid for the project with Pacific Bridge Company of Portland, Oregon ; Henry J. Kaiser & W. A. Bechtel Company of San Francisco; MacDonald & Kahn Ltd. of Los Angeles; and the J.F. Shea Company of Portland, Oregon. The joint venture was called Six Companies, Inc. as Bechtel and Kaiser were considered one company for purposes of Six in
14628-588: The number of black people employed by Six Companies never exceeded thirty, mostly lowest-pay-scale laborers in a segregated crew, who were issued separate water buckets. As part of the contract, Six Companies, Inc. was to build Boulder City to house the workers. The original timetable called for Boulder City to be built before the dam project began, but President Hoover ordered work on the dam to begin in March 1931 rather than in October. The company built bunkhouses, attached to
14766-424: The operation is the same as double-clutching, but it requires neutral be held slightly longer than a single-gear change. Common North American setups include 9, 10, 13, 15, and 18 speeds. Automatic and automated manual transmissions for heavy trucks are becoming more and more common, due to advances both in transmission and engine power. In Europe, 8, 10, 12, and 16 gears are common on larger trucks with
14904-440: The penstocks for maintenance. Following an uprating project from 1986 to 1993, the total gross power rating for the plant, including two 2.4 megawatt Pelton turbine -generators that power Hoover Dam's own operations is a maximum capacity of 2080 megawatts. The annual generation of Hoover Dam varies. The maximum net generation was 10.348 TWh in 1984, and the minimum since 1940 was 2.648 TWh in 1956. The average power generated
15042-531: The potential for uneven cooling and contraction of the concrete posed a serious problem. Bureau of Reclamation engineers calculated that if the dam were to be built in a single continuous pour, the concrete would take 125 years to cool, and the resulting stresses would cause the dam to crack and crumble. Instead, the ground where the dam would rise was marked with rectangles, and concrete blocks in columns were poured, some as large as 50 ft square (15 m) and 5 feet (1.5 m) high. Each five-foot form contained
15180-471: The powerhouse was carried out simultaneously with the excavation for the dam foundation and abutments. The excavation of this U-shaped structure located at the downstream toe of the dam was completed in late 1933 with the first concrete placed in November 1933. Filling of Lake Mead began February 1, 1935, even before the last of the concrete was poured that May. The powerhouse was one of the projects uncompleted at
15318-475: The project, together with their families. Another camp, on the flats along the Colorado River, was officially called Williamsville, but was known to its inhabitants as "Ragtown". When construction began, Six Companies hired large numbers of workers, with more than 3,000 on the payroll by 1932 and with employment peaking at 5,251 in July 1934. "Mongolian" (Chinese) labor was prevented by the construction contract, while
15456-445: The remainder were talked into leaving by law enforcement. On August 13, the company began hiring workers again, and two days later, the strike was called off. While the workers received none of their demands, the company guaranteed there would be no further reductions in wages. Living conditions began to improve as the first residents moved into Boulder City in late 1931. A second labor action took place in July 1935, as construction on
15594-561: The roughest treatment and extreme overloading. British soldiers nicknamed the AC the "Bulldog", a reference to the model's tenacity and its stub nose, and the nickname was later also adopted by US troops. As a result of this nickname earned by the AC on the Western Front , all Mack trucks were often referred to as "Bulldogs", and in 1922 the company adopted the Bulldog as its corporate symbol. The AC proved to be an extremely enduring model for Mack and it remained in production until 1938, with
15732-504: The side-walls were also excavated to reach virgin rock, as weathered rock might provide pathways for water seepage. Shovels for the excavation came from the Marion Power Shovel Company . The men who removed this rock were called "high scalers". While suspended from the top of the canyon with ropes, the high-scalers climbed down the canyon walls and removed the loose rock with jackhammers and dynamite . Falling objects were
15870-477: The situation. It found that the work had been incompletely done, and was based on less than a full understanding of the canyon's geology. New holes were drilled from inspection galleries inside the dam into the surrounding bedrock. It took nine years (1938–47) under relative secrecy to complete the supplemental grout curtain. The first concrete was poured into the dam on June 6, 1933, 18 months ahead of schedule. Since concrete heats and contracts as it cures,
16008-442: The supervising architect to the Bureau of Reclamation, was brought in to redesign the exteriors. Kaufmann greatly streamlined the design and applied an elegant Art Deco style to the entire project. He designed sculpted turrets rising seamlessly from the dam face and clock faces on the intake towers set for the time in Nevada and Arizona—both states are in different time zones, but since Arizona does not observe daylight saving time ,
16146-470: The time of the formal dedication on September 30, 1935; a crew of 500 men remained to finish it and other structures. To make the powerhouse roof bombproof, it was constructed of layers of concrete, rock, and steel with a total thickness of about 3.5 feet (1.1 m), topped with layers of sand and tar. In the latter half of 1936, water levels in Lake Mead were high enough to permit power generation, and
16284-575: The truck can have on the Interstate highway system. Each State determines the maximum permissible vehicle , combination , and axle weight on state and local roads. Uniquely, the State of Michigan has a gross vehicle weight limit of 164,000 lb (74 t), which is twice the U.S. federal limit. A measure to change the law was defeated in the Michigan Senate in 2019. Almost all trucks share
16422-447: The tunnels for maintenance. To protect the construction site from the Colorado River and to facilitate the river's diversion, two cofferdams were constructed. Work on the upper cofferdam began in September 1932, even though the river had not yet been diverted. The cofferdams were designed to protect against the possibility of the river's flooding a site at which two thousand men might be at work, and their specifications were covered in
16560-451: The tunnels with concrete. First the base, or invert, was poured. Gantry cranes , running on rails through the entire length of each tunnel were used to place the concrete. The sidewalls were poured next. Movable sections of steel forms were used for the sidewalls. Finally, using pneumatic guns, the overheads were filled in. The concrete lining is 3 feet (1 m) thick, reducing the finished tunnel diameter to 50 ft (15 m). The river
16698-422: The tunnels with large concrete plugs. The downstream halves of the tunnels following the inner plugs are now the main bodies of the spillway tunnels. The inner diversion tunnels were plugged at approximately one-third of their length, beyond which they now carry steel pipes connecting the intake towers to the power plant and outlet works. The inner tunnels' outlets are equipped with gates that can be closed to drain
16836-405: The use of diesel engines in heavy trucks. CNG engines are widely used in the US refuse industry and in concrete mixers, among other short-range vocations, but range limitations have prevented their broader uptake in freight hauling applications. Heavy electric trucks and hydrogen-powered trucks are new to the market in 2021, but major freight haulers are interested. Although cars will be first
16974-447: The vehicle. Smaller varieties may be mechanically similar to some automobiles . Commercial trucks can be very large and powerful and may be configured to be mounted with specialized equipment, such as in the case of refuse trucks , fire trucks , concrete mixers , and suction excavators . In American English, a commercial vehicle without a trailer or other articulation is formally a "straight truck" while one designed specifically to pull
17112-615: The watchers. The high scalers received considerable media attention, with one worker dubbed the "Human Pendulum" for swinging co-workers (and, at other times, cases of dynamite) across the canyon. To protect themselves against falling objects, some high scalers dipped cloth hats in tar and allowed them to harden. When workers wearing such headgear were struck hard enough to inflict broken jaws, they sustained no skull damage. Six Companies ordered thousands of what initially were called "hard boiled hats" (later " hard hats ") and strongly encouraged their use. The cleared, underlying rock foundation of
17250-432: Was 4.2 TWh/year for 1947–2008. In 2015, the dam generated 3.6 TWh. The amount of electricity generated by Hoover Dam has been decreasing along with the falling water level in Lake Mead due to the prolonged drought since year 2000 and high demand for the Colorado River's water. By 2014 its generating capacity was downrated by 23% to 1592 MW and was providing power only during periods of peak demand. Lake Mead fell to
17388-457: Was a shaft driven version of the AC, produced between 1927 and 1936. The Mack AP was a version of the AC with a 6-cylinder engine that was produced between 1926 and 1938. The AP was available in either four or six wheeled versions; the four-wheeler had a payload of 7 + 1 ⁄ 2 long tons (7.6 t), the six-wheeler a payload of 10 long tons (10 t) in rigid form and 15 long tons (15 t) as an articulated truck . The Mack AL
17526-435: Was a version of the AC model and designed specifically for distribution operations and firefighting equipment. This model differed by low mounted cabin and low frame height. Total of only 57 such vehicles were made, produced between 1927 and 1929. The Mack AC saw extensive service with the militaries of the United States and the United Kingdom during the First World War . During the war Mack delivered approximately 4,500 ACs to
17664-418: Was a visitor to the site; the remainder were employees of various contractors not part of Six Companies. Ninety-six of the deaths occurred during construction at the site. Not included in the official number of fatalities were deaths that were recorded as pneumonia . Workers alleged that this diagnosis was a cover for death from carbon monoxide poisoning (brought on by the use of gasoline-fueled vehicles in
17802-446: Was awarded two patents for their design. These buckets, which weighed 20 short tons (18.1 t; 17.9 long tons) when full, were filled at two massive concrete plants on the Nevada side, and were delivered to the site in special railcars . The buckets were then suspended from aerial cableways which were used to deliver the bucket to a specific column. As the required grade of aggregate in the concrete differed depending on placement in
17940-428: Was diverted into the two Arizona tunnels on November 13, 1932; the Nevada tunnels were kept in reserve for high water. This was done by exploding a temporary cofferdam protecting the Arizona tunnels while at the same time dumping rubble into the river until its natural course was blocked. Following the completion of the dam, the entrances to the two outer diversion tunnels were sealed at the opening and halfway through
18078-444: Was in 1611 when it referred to the small strong wheels on ships' cannon carriages, and comes from "Trokhos" (Greek) = "wheel". In its extended usage, it came to refer to carts for carrying heavy loads, a meaning known since 1771. Its expanded application to "motor-powered load carrier" has been in usage since 1930, shortened from "motor truck", which dates back to 1901. "Lorry" has a more uncertain origin, but probably has its roots in
18216-452: Was named Boulder Dam by the Roosevelt administration. In 1947, the name Hoover Dam was restored by Congress . Since about 1900, the Black Canyon and nearby Boulder Canyon had been investigated for their potential to support a dam that would control floods, provide irrigation water, and produce hydroelectric power . In 1928, Congress authorized the project. The winning bid to build the dam
18354-469: Was necessary to remove accumulated erosion soils and other loose materials in the riverbed until sound bedrock was reached. Work on the foundation excavations was completed in June 1933. During this excavation, approximately 1,500,000 cu yd (1,100,000 m ) of material was removed. Since the dam was an arch-gravity type, the side-walls of the canyon would bear the force of the impounded lake. Therefore,
18492-507: Was no space for a construction camp at the bottom of the canyon or for a spillway. The Service investigated Black Canyon and found it ideal; a railway could be laid from the railhead in Las Vegas to the top of the dam site. Despite the site change, the dam project was referred to as the "Boulder Canyon Project". With little guidance on water allocation from the Supreme Court , proponents of
18630-541: Was not common in trucks in Europe until the 1930s. In the United States, Autocar introduced diesel engines for heavy applications in the mid-1930s. Demand was high enough that Autocar launched the "DC" model (diesel conventional) in 1939. However, it took much longer for diesel engines to be broadly accepted in the US: gasoline engines were still in use on heavy trucks in the 1970s. Electrically powered trucks predate internal combustion ones and have been continuously available since
18768-430: Was powered by a pair-cast 4-cylinder petrol engine that delivered 74 brake horsepower (55 kW) (5x6 471.2ci). The engine had an aluminum crankcase which included inspection ports, and a governor built into the camshaft timing gear ; it was driven through a three-speed transmission with a clutch brake . From 1936 Buda and Cummins diesel engines were also offered in the AC. One of the most distinctive features of
18906-467: Was submitted by a consortium named Six Companies, Inc. , which began construction in early 1931. Such a large concrete structure had never been built before, and some of the techniques used were unproven. The torrid summer weather and lack of facilities near the site also presented difficulties. Nevertheless, Six Companies turned the dam over to the federal government on March 1, 1936, more than two years ahead of schedule. Hoover Dam impounds Lake Mead and
19044-512: Was to accompany each bid; the winner would have to post a $ 5 million performance bond . The contractor had seven years to build the dam, or penalties would ensue. The Wattis Brothers , heads of the Utah Construction Company , were interested in bidding on the project, but lacked the money for the performance bond. They lacked sufficient resources even in combination with their longtime partners, Morrison-Knudsen , which employed
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