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75-614: The Allison V730 is a three-speed automatic transmission used in several makes of transit bus including the RTS , Canadian-produced Classic buses derived from the GM New Look , and Grumman Flxibles . Later production buses in the GM and Flxible line had the Allison V731 transmission, which is essentially the same unit but controlled electronically, with a keypad replacing the familiar shifter-lever in

150-425: A p − R s tan ⁡ a s ) + w t Q A ρ ( R t tan ⁡ a t − R p tan ⁡ a p ) + w s Q A ρ ( R s tan ⁡

225-1025: A s − R t tan ⁡ a t ) − P L {\displaystyle \rho (S_{\mathrm {p} }{\dot {w_{\mathrm {p} }}}+S_{\mathrm {t} }{\dot {w_{\mathrm {t} }}}+S_{\mathrm {s} }{\dot {w_{\mathrm {s} }}})+\rho {\frac {L_{\mathrm {f} }}{A}}{\dot {Q}}=\rho (R_{\mathrm {p} }^{2}w_{\mathrm {p} }^{2}+R_{\mathrm {t} }^{2}w_{\mathrm {t} }^{2}+R_{\mathrm {s} }^{2}w_{\mathrm {s} }^{2}-R_{\mathrm {s} }^{2}w_{\mathrm {p} }w_{\mathrm {s} }-R_{\mathrm {p} }^{2}w_{\mathrm {t} }w_{\mathrm {p} }-R_{\mathrm {t} }^{2}w_{\mathrm {s} }w_{\mathrm {t} })+w_{\mathrm {p} }{\frac {Q}{A}}\rho (R_{\mathrm {p} }\tan {a_{\mathrm {p} }}-R_{\mathrm {s} }\tan {a_{\mathrm {s} }})+w_{\mathrm {t} }{\frac {Q}{A}}\rho (R_{\mathrm {t} }\tan {a_{\mathrm {t} }}-R_{\mathrm {p} }\tan {a_{\mathrm {p} }})+w_{\mathrm {s} }{\frac {Q}{A}}\rho (R_{\mathrm {s} }\tan {a_{\mathrm {s} }}-R_{\mathrm {t} }\tan {a_{\mathrm {t} }})-P_{L}} where A simpler correlation

300-455: A prime mover , like an internal combustion engine , to a rotating driven load. In a vehicle with an automatic transmission , the torque converter connects the prime mover to the automatic gear train, which then drives the load. It is thus usually located between the engine's flexplate and the transmission. The equivalent device in a manual transmission is the mechanical clutch . A torque converter serves to increase transmitted torque when

375-459: A DC-DC converter, a solid-state device that converts the high-voltage traction motor energy to 12/24V accessory power. As of 2008, there are more than 2,700 GM-Allison hybrid buses operating in 81 cities in the U.S., Canada and Europe. This includes: Allison introduced its second-generation eGen Flex diesel-electric hybrid drive unit in 2022, partnering with Gillig ; the first units will be delivered to IndyGo , serving Indianapolis. eGen Flex

450-399: A basic fluid coupling the theoretical torque capacity of a converter is proportional to r N 2 D 5 {\displaystyle r\,N^{2}D^{5}} , where r {\displaystyle r} is the mass density of the fluid (kg/m ), N {\displaystyle N} is the impeller speed ( rpm ), and D {\displaystyle D}

525-439: A continuously variable transmission controlled electronically; it integrates two motor-generators (MG-A and MG-B, on the input and output, respectively), three planetary gear sets (P1, P2, and P3), one rotating clutch (C2), and one stationary clutch (C1). From the engine, power is transferred to the input shaft through a torque damper instead of the conventional torque converter found in an automatic transmission. The input shaft

600-463: A conventional bus. To the operator, the hybrid system is automatic and requires no special training. Under normal in-motion operation, engine speed is controlled by the TCM, which commands a torque and speed point based on the needs of the hybrid system. During startup and shutdown, the TCM commands only a speed requirement. The E Drive Unit is installed in lieu of a conventional transmission and acts as

675-404: A design feature that eases the process of inspection and repair, but adds to the cost of producing the converter. In high performance, racing and heavy duty commercial converters, the pump and turbine may be further strengthened by a process called furnace brazing , in which molten brass is drawn into seams and joints to produce a stronger bond between the blades, hubs and annular ring(s). Because

750-429: A feature beyond what a simple fluid coupling provides, which can match rotational speed but does not multiply torque. Fluid-coupling–based torque converters also typically include a lock-up function to rigidly couple input and output and avoid the efficiency losses associated with transmitting torque by fluid flow when operating conditions permit. By far the most common form of torque converter in automobile transmissions

825-959: A heavier-duty version, the HT-740, was introduced; the new MT and HT were both derived from the AT-540. As an option, the MT-6 nn and HT-7 nn series transmissions could be equipped with a lower fifth gear for severe off-road conditions. In 1970, GM combined the Allison and Detroit Diesel divisions as the Detroit Diesel Allison Division of GM . The 500-series transmissions (AT-540, etc.) were rated to accept input power of up to 235 hp (175 kW) and were intended for vehicles up to 30,000 lb (14,000 kg) gross vehicle weight (GVW). The medium-duty 600-series had increased ratings to 300 hp (220 kW) and 73,280 lb (33,240 kg) GVW, while

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900-413: A line of motor-integrated electric axles, branded eGen Power . The first model, 100D, was designated for its gross axle weight rating (GAWR) of 10.4 t (23,000 lb) and (D)ual electric motors; 100D has a continuous and peak power output of 424 and 648 kW (569 and 869 hp), respectively, with a maximum torque of 46,800 N⋅m (34,500 lbf⋅ft). In 2021, Allison expanded the range with

975-541: A presence in more than 150 countries and manufacturing facilities in Indianapolis, Chennai , India , and Szentgotthárd , Hungary . Allison began in 1909 when James A. Allison , along with three business partners, helped fund and build the Indianapolis Motor Speedway . In 1911, Allison's new track held the first Indianapolis 500 mile race. In addition to funding several race teams, James Allison founded

1050-503: A second-generation lighter-duty automatic transmission, the four-speed AT-540, which Allison developed jointly with Hydramatic Division in the late 1960s; the AT-540 was targeted specifically for on-highway use and shared similarities with automobile transmissions to reduce the cost penalty to equip on-highway trucks with automatic transmissions. Later, the MT-25 itself was replaced by the MT-640 and

1125-493: A specific family: GM-Allison introduced hybrid vehicle technology for transit buses in 2003. Allison hybrid transit bus products were initially branded as the Allison Electric Drives E System , which included the following components: Allison characterizes the system as the "Two-Mode Compound Split Parallel Hybrid Architecture" . As installed in buses, the E System has two operating modes or speed ranges, with

1200-403: A storage capacity of 450 A and 624 VDC. Each sub-string uses two 312 V sub-packs in series, which are made of 40 7.8-volt modules. Six battery control information modules (BCIM) monitor temperature, one in each sub-pack. The DPIM and ESS have been improved since the initial introduction, and newer models generally can replace earlier units. In addition, newer installations include

1275-430: A vehicle with an automatic transmission is stopped at a traffic signal or in traffic congestion while still in gear). A torque converter cannot achieve 100 percent coupling efficiency. The classic three element torque converter has an efficiency curve that resembles ∩: zero efficiency at stall, generally increasing efficiency during the acceleration phase and low efficiency in the coupling phase. The loss of efficiency as

1350-426: A wider range of torque multiplication. Such multiple-element converters are more common in industrial environments than in automotive transmissions, but automotive applications such as Buick 's Triple Turbine Dynaflow and Chevrolet 's Turboglide also existed. The Buick Dynaflow utilized the torque-multiplying characteristics of its planetary gear set in conjunction with the torque converter for low gear and bypassed

1425-435: Is available as multiple models, designated eGen Flex 40, 40 CertPlus, 40 Max, or 40 Max CertPlus (equivalent to the H 40 in physical size, input, and output capabilities); or the eGen Flex 50, 50 CertPlus, 50 Max, or 50 Max CertPlus (equivalent to the H 50). The "Max" models are capable of operating on electric power alone for up to 10 mi (16 km), depending on the axle ratio and duty cycle. In 2020, Allison introduced

1500-424: Is coupled to the main shaft and MG-A through the first planetary gearset (P1), and MG-A is coupled to MG-B through another planetary gearset (P2). MG-B is coupled to the output shaft through a third planetary gearset (P3) and the stationary (C1) and rotating (C2) clutches. Both motors are three-phase AC induction motors and automatically switch from motoring to generation when the mechanical rotation frequency exceeds

1575-622: Is due to the presence of the stator (even though rotating as part of the assembly), as it always generates some power-absorbing turbulence. Most of the loss, however, is caused by the curved and angled turbine blades, which do not absorb kinetic energy from the fluid mass as well as radially straight blades. Since the turbine blade geometry is a crucial factor in the converter's ability to multiply torque, trade-offs between torque multiplication and coupling efficiency are inevitable. In automotive applications, where steady improvements in fuel economy have been mandated by market forces and government edict,

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1650-409: Is prevented by the one-way stator clutch . Unlike the radially straight blades used in a plain fluid coupling, a torque converter's turbine and stator use angled and curved blades. The blade shape of the stator is what alters the path of the fluid, forcing it to coincide with the impeller rotation. The matching curve of the turbine blades helps to correctly direct the returning fluid to the stator so

1725-416: Is provided by Kotwicki. A fluid coupling is a two-element drive that is incapable of multiplying torque, while a torque converter has at least one extra element—the stator—which alters the drive's characteristics during periods of high slippage, producing an increase in output torque. In a torque converter there are at least three rotating elements: the impeller, which is mechanically driven by

1800-440: Is the diameter ( m ). In practice, the maximum torque capacity is limited by the mechanical characteristics of the materials used in the converter's components, as well as the ability of the converter to dissipate heat (often through water cooling). As an aid to strength, reliability and economy of production, most automotive converter housings are of welded construction. Industrial units are usually assembled with bolted housings,

1875-500: Is the hydrodynamic device described above. There are also hydrostatic systems which are widely used in small machines such as compact excavators . There are also mechanical designs for torque converters, many of which are similar to mechanical continuously variable transmissions or capable of acting as such as well. They include the pendulum-based Constantinesco torque converter , the Lambert friction gearing disk drive transmission and

1950-481: The Variomatic with expanding pulleys and a belt drive. Torque converter equations of motion are governed by Leonhard Euler 's eighteenth century turbomachine equation : The equation expands to include the fifth power of radius; as a result, torque converter properties are very dependent on the size of the device. Mathematical formulations for the torque converter are available from several authors. Hrovat derived

2025-532: The Allison Engine Company , a major force in aviation. Plant 3 was built in 1939, a 360,000 sq ft (33,000 m ) factory to build V1710 engines. Due to demand during World War II , Allison would add a second factory (Plant 5) and 23,000 new employees; by the end of the war, Allison had built 70,000 V1710 engines. Alongside the development and production of the V1710, engineers at GM began designing

2100-472: The Budd Rail Diesel Car , which first went into service in 1950. Pairing with a GM Series 110 "pancake" diesel engine mounted under the railcar floor enabled the entire power system to be kept outside the car body, making the full length of the car available for revenue. The torque converter enabled unprecedented rates of acceleration before locking into direct drive. At approximately the same time

2175-577: The Buick Dynaflow and Chevrolet Turboglide could produce more). Specialized converters designed for industrial, rail, or heavy marine power transmission systems are capable of as much as 5.0:1 multiplication. Generally speaking, there is a trade-off between maximum torque multiplication and efficiency—high stall ratio converters tend to be relatively inefficient around the coupling speed, whereas low stall ratio converters tend to provide less possible torque multiplication. The characteristics of

2250-491: The Buick Dynaflow automatic transmission was a non-shifting design and, under normal conditions, relied solely upon the converter to multiply torque. The Dynaflow used a five-element converter to produce the wide range of torque multiplication needed to propel a heavy vehicle. Although not strictly a part of classic torque converter design, many automotive converters include a lock-up clutch to improve cruising power transmission efficiency and reduce heat. The application of

2325-738: The DDA 6V92TA two-stroke diesel engine, with the exception of GM 'Classic' T6H-5307 buses produced in Canada, where these were instead mated to the then-standard 6V71N engine. Some Canadian production 1982 "New Look" models featured the 6V92 mated to the V730, such as Vancouver, B.C.'s 1982 T6H-5307 "Hillclimber" buses. An example resides at "TRAMS" in British Columbia. Allison Transmission With headquarters in Indianapolis, Indiana , Allison Transmission has

Allison V730 - Misplaced Pages Continue

2400-603: The Liberty airplane engine — the main power plant used in the U.S. war effort. After the war, Allison entered a car in the 1919 Indy 500 and won. It was the last race Allison's team ever entered as he turned his company's attention to aviation engineering, renaming it to Allison Engineering Company ; the aviation-focused company developed steel-backed bronze sleeve bearings for the crankshaft and connecting rods, and high-speed reduction gearing to turn propellers and Roots-type blowers . The company's reputation and expertise in aviation

2475-646: The Speedway Racing Team Company on September 14, 1915 and quickly gained a reputation for his work on race cars and automotive technology in general. Allison built a shop near the track and changed the team's name to the Allison Experimental Company ; the shop later became Plant No. 1. When World War I began, Allison suspended racing, and the Allison Experimental Company began machining parts, tools, and masters for

2550-422: The prime mover ; the turbine, which drives the load ; and the stator, which is interposed between the impeller and turbine so that it can alter oil flow returning from the turbine to the impeller. The classic torque converter design dictates that the stator be prevented from rotating under any condition, hence the term stator . In practice, however, the stator is mounted on an overrunning clutch , which prevents

2625-469: The 1000/2000 Series transmission family; transmissions within a family share the same basic dimensions, power input capabilities, and weight. Allison transmission families include the 1000/2000 Series, 3000 Series, 4000 Series, 5000 Series, 6000 Series, 8000 Series, 9000 Series, and Tractor Series. Each transmission family is given a generational designation based on the electronic control system; parts generally are not interchangeable between generations within

2700-507: The 100S (a single-motor variant of the 100D, with continuous and peak power output of 212 and 324 kW (284 and 434 hp), respectively and a maximum 23,500 N⋅m (17,300 lbf⋅ft) of torque) and the 130D (a variant of the 100D with a higher 13 t (29,000 lb) GAWR for the European and Asia Pacific markets). The Allison eGen Power integrated axle also includes a multi-speed gearbox to optimize both launch and cruising speeds; it

2775-532: The 3000 and 4000 Series, respectively. As of 1998 in the United States, Allison had built 92% of the transmissions in school buses; 75% of transit bus transmissions, 65% of heavy-duty garbage truck transmissions, and 32% of all medium-duty truck transmissions. Allison followed the WT (3000 and 4000 Series) line with the 1000 and 2000 Series starting in 1999. The 1000 Series transmission incorporated many features from

2850-401: The Allison hybrid system is in recapturing kinetic energy during regenerative braking and storing it as electrical energy, which can later be converted back to kinetic energy through an output motor, which assists in accelerating the vehicle, reducing demand on the engine and consequently fuel consumption. Fuel economy is improved by up to 60%, and acceleration can also be improved compared to

2925-576: The CD-850 cross-drive steering transmission for tracked military vehicles in 1941; the design was completed in 1944 and Allison was awarded the contract to manufacture the prototypes. In February 1945, General Motors formed the Allison Transmission Engineering Section , dividing the subsidiary into Aircraft Operations and Transmission Operations in 1946. The CD-850 combined range change, steering and braking. Allison stopped producing

3000-491: The CD-850 in 1986, but a licensed version was produced in Spain for more than a decade afterward. General Motors began developing automatic transmissions with a hydraulic torque converter in the 1930s under its Product Study Group, offering it as an option for Oldsmobile for the first time in 1940. After World War II, Allison Transmission turned its attention to civilian transportation. Allison designed, developed and manufactured

3075-513: The CD-850 was going into production, GMC Truck and Coach Division requested that GM develop a V-Drive transmission with a torque converter in 1945 for transit bus use, replacing the Spicer manual transmission then offered. These buses had rear-mounted engines and to maximize passenger space, the engine compartment was minimized; the V-Drive transmission was named for the 63° angle of intersection between

Allison V730 - Misplaced Pages Continue

3150-563: The MT-25, which designated the intended application ("M"edium "T"rucks) and maximum input power, 250 hp (190 kW). The MT-25 was a 6-speed automatic, using a two-speed high/low splitter and three-speed double planetary gear train. The splitter was equipped with a hydraulic retarder . Because of the additional cost of the automatic transmission, sales were initially slow until Allison began targeting specific markets that required both on- and off-road driving as well as frequent stops and starts, such as concrete mixing and garbage trucks in

3225-492: The TT ;2220 was a twin-turbine 2000 series automatic transmission with two forward speeds and a maximum input torque capacity of 250 lb⋅ft (340 N⋅m). 39°46′46.92″N 86°14′12.39″W  /  39.7797000°N 86.2367750°W  / 39.7797000; -86.2367750 Torque converter A torque converter is a device, usually implemented as a type of fluid coupling , that transfers rotating power from

3300-493: The WT line for light-duty trucks, including the electronic control system, and was initially available as an option with the 6.6L GM/Isuzu Duramax diesel engine and the 8.1L Vortec gasoline engine for the trucks based on the GMT800 platform. In 2007, GM sold Allison Transmission to private equity firms Carlyle Group and Onex Corporation for US$ 5.6 billion. Allison markets its transmissions by vocational series according to

3375-451: The changeover generally occurring between 15 and 25 mph (24 and 40 km/h). Under full-throttle, the vehicle's initial launch in the low-speed mode is boosted by the output motor. As vehicle speed increases, the input motor begins to dominate, resulting in nearly total mechanical output only. Through 2011, GM intended to introduce 16 passenger car and truck hybrid models based on the Allison split-mode system. The primary benefit of

3450-399: The clutch locks the turbine to the impeller, causing all power transmission to be mechanical, thus eliminating losses associated with fluid drive. A torque converter has three stages of operation: The key to the torque converter's ability to multiply torque lies in the stator. In the classic fluid coupling design, periods of high slippage cause the fluid flow returning from the turbine to

3525-468: The converter at cruising speeds, unlocking when the throttle was floored for quick acceleration or as the vehicle slowed. This feature was also present in some Borg-Warner transmissions produced during the 1950s. It fell out of favor in subsequent years due to its extra complexity and cost. In the late 1970s lock-up clutches started to reappear in response to demands for improved fuel economy, and are now nearly universal in automotive applications. As with

3600-400: The converter enters the coupling phase is a result of the turbulence and fluid flow interference generated by the stator, and as previously mentioned, is commonly overcome by mounting the stator on a one-way clutch. Even with the benefit of the one-way stator clutch, a converter cannot achieve the same level of efficiency in the coupling phase as an equivalently sized fluid coupling. Some loss

3675-621: The driver's compartment. The Allison V730/V731 family transmissions moreover come in versions with a built-in retarder (the VR731), and a version allowing transit agencies and others to use right-turning Detroit Diesel family motors (variously the V731R or V731RH) instead of the standard left-turning units found in Flxibles, GM New Looks and RTS equipment. Most installations of the V730/V731 have them coupled to

3750-475: The early 1960s. The MT-25 was fitted first as an option branded Powermatic by Powermatic, exclusive to that brand for the first year, but was soon offered by other truck manufacturers including Ford (1957), Reo (1958), Dodge (1958), Diamond T (1959), White (1961), and International Harvester (1961); production of the MT-25 continued into the early 1970s. The MT-25 was supplemented in September 1970 by

3825-401: The energy being applied to the impeller by the prime mover. This action causes a substantial increase in the mass of fluid being directed to the turbine, producing an increase in output torque. Since the returning fluid is initially traveling in a direction opposite to impeller rotation, the stator will likewise attempt to counter-rotate as it forces the fluid to change direction, an effect that

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3900-3687: The equations of the pump, turbine, stator, and conservation of energy. Four first-order differential equations can define the performance of the torque converter. I i ω i ˙ + ρ S i Q ˙ = − ρ ( ω i R i 2 + R i Q A tan ⁡ α i − ω s R s 2 − R s Q A tan ⁡ α s ) Q + τ i {\displaystyle I_{i}{\dot {\omega _{i}}}+\rho S_{i}{\dot {Q}}=-\rho (\omega _{i}R_{i}^{2}+R_{i}{\frac {Q}{A}}\tan {\alpha _{i}}-\omega _{\mathrm {s} }R_{\mathrm {s} }^{2}-R_{\mathrm {s} }{\frac {Q}{A}}\tan {\alpha _{\mathrm {s} }})Q+\tau _{i}} I t ω t ˙ + ρ S t Q ˙ = − ρ ( ω t R t 2 + R t Q A tan ⁡ α t − ω i R i 2 − R i Q A tan ⁡ α i ) Q + τ t {\displaystyle I_{\mathrm {t} }{\dot {\omega _{\mathrm {t} }}}+\rho S_{\mathrm {t} }{\dot {Q}}=-\rho (\omega _{\mathrm {t} }R_{\mathrm {t} }^{2}+R_{\mathrm {t} }{\frac {Q}{A}}\tan {\alpha _{\mathrm {t} }}-\omega _{i}R_{i}^{2}-R_{i}{\frac {Q}{A}}\tan {\alpha _{i}})Q+\tau _{\mathrm {t} }} I s ω s ˙ + ρ S s Q ˙ = − ρ ( ω s R s 2 + R s Q A tan ⁡ α s − ω t R t 2 − R t Q A tan ⁡ α t ) Q + τ s {\displaystyle I_{\mathrm {s} }{\dot {\omega _{\mathrm {s} }}}+\rho S_{\mathrm {s} }{\dot {Q}}=-\rho (\omega _{\mathrm {s} }R_{\mathrm {s} }^{2}+R_{\mathrm {s} }{\frac {Q}{A}}\tan {\alpha _{\mathrm {s} }}-\omega _{\mathrm {t} }R_{\mathrm {t} }^{2}-R_{\mathrm {t} }{\frac {Q}{A}}\tan {\alpha _{\mathrm {t} }})Q+\tau _{\mathrm {s} }} ρ ( S p w p ˙ + S t w t ˙ + S s w s ˙ ) + ρ L f A Q ˙ = ρ ( R p 2 w p 2 + R t 2 w t 2 + R s 2 w s 2 − R s 2 w p w s − R p 2 w t w p − R t 2 w s w t ) + w p Q A ρ ( R p tan ⁡

3975-523: The first major contract being for 900 buses in 1948, for New York City . The VS-2 was introduced in 1955, which added a two-speed input splitter; a version with both hydraulic and direct clutches was introduced in 1958 (VH), and production of the original V-Drive transmissions was concluded in July 1976, with 65,389 produced. In addition to the transit bus market, Allison began developing automatic transmissions for commercial trucks in 1953. This effort resulted in

4050-428: The first turbine, using only the second turbine as vehicle speed increased. The unavoidable trade-off with this arrangement was low efficiency and eventually these transmissions were discontinued in favor of the more efficient three speed units with a conventional three element torque converter. It is also found that efficiency of torque converter is maximum at very low speeds. As described above, impelling losses within

4125-459: The first-ever automatic transmissions for heavy-duty vehicles including delivery trucks, city buses, and railcars, starting from 1948. In addition, Allison marketed transmissions for off-highway heavy-duty vehicles under the brand Powershift TORQMATIC, with the first TG series transmissions being produced in July 1948. The Allison 850-series torque converter was a crucial component in the post-war development of self-propelled railcars, most notably

4200-456: The fluid's kinetic energy will be lost due to friction and turbulence, causing the converter to generate waste heat (dissipated in many applications by water cooling). This effect, often referred to as pumping loss, will be most pronounced at or near stall conditions. In modern designs, the blade geometry minimizes oil velocity at low impeller speeds, which allows the turbine to be stalled for long periods with little danger of overheating (as when

4275-451: The heavy-duty 700-series were rated to 445 hp (332 kW) and 80,000 lb (36,000 kg) GVW. In 1976, a 700-series V-Drive transmission was introduced for buses, the V730 . The AT/MT/HT were still being produced in 1998. Allison also produced off-highway transmissions in the 1960s, starting with the "Dual Path Powershift" DP 8000 series. The first electronic controls were fitted to

4350-410: The impeller to oppose the direction of impeller rotation, leading to a significant loss of efficiency and the generation of considerable waste heat . Under the same condition in a torque converter, the returning fluid will be redirected by the stator so that it aids the rotation of the impeller, instead of impeding it. The result is that much of the energy in the returning fluid is recovered and added to

4425-715: The intended use; for example, the Tractor Series is sold for and installed in Class 8 tractors , while the Motorhome Series is marketed to manufacturers of recreational vehicles . A transmission is given a designation specific to the vocational series, but is otherwise identical mechanically to other transmissions sold for other vocational series; for example, the Bus Series B210 / B220 / B295 transmissions are also sold with identical gearing as: Collectively, these are grouped into

4500-419: The latter can do its job. The shape of the blades is important as minor variations can result in significant changes to the converter's performance. During the stall and acceleration phases, in which torque multiplication occurs, the stator remains stationary due to the action of its one-way clutch. However, as the torque converter approaches the coupling phase, the energy and volume of the fluid returning from

4575-447: The mid-1980s, prior to the sale of Detroit Diesel to Roger Penske in 1987. The WT used the WT electronic control (WTEC) system to control the internal clutches during shifting, equipped with a control unit that adapts to variations during use. The WT line was split into MD (medium duty), HD (heavy duty, introduced in 1993), and B (T-drive buses) lines; the MD and HD lines were later renamed to

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4650-520: The nearly universal use of a lock-up clutch has helped to eliminate the converter from the efficiency equation during cruising operation. The maximum amount of torque multiplication produced by a converter is highly dependent on the size and geometry of the turbine and stator blades, and is generated only when the converter is at or near the stall phase of operation. Typical stall torque multiplication ratios range from 1.8:1 to 2.5:1 for most automotive applications (although multi-element designs as used in

4725-546: The off-highway DP 8000 series transmission in 1971. Electronic controls (branded the Allison Transmission Electronic Control or ATEC system) were added to the MT/HT/V730 in 1983, improving fuel economy by more precisely controlling shifts. The third-generation six-speed World Transmission (WT) was introduced in 1991, replacing the second-generation AT/MT/HT/V730 lines. Development of the WT had begun in

4800-400: The output rotational speed is low. In the fluid coupling embodiment, it uses a fluid, driven by the vanes of an input impeller, and directed through the vanes of a fixed stator, to drive an output turbine in such a manner that torque on the output is increased when the output shaft is rotating more slowly than the input shaft, thus providing the equivalent of an adaptive reduction gear . This is

4875-429: The power band of the engine more quickly. Highway vehicles generally use lower stall torque converters to limit heat production, and provide a more firm feeling to the vehicle's characteristics. A design feature once found in some General Motors automatic transmissions was the variable-pitch stator, in which the blades' angle of attack could be varied in response to changes in engine speed and load. The effect of this

4950-412: The respective H50 input limits are 330 hp (250 kW) and 1,050 lb⋅ft (1,420 N⋅m). The DPIM includes an inverter for each motor; the continuous and peak output are 160 and 300 kW, respectively. The ESS uses nickel-metal hydride batteries, air-cooled using internal fans, and weighs approximately 915 lb (415 kg). The ESS is made of three sub-strings wired in parallel with

5025-539: The stator field frequency. There are two drive units available (EP40 or H 40 EP; and EP50 or H 50 EP). The H40 is intended for regular transit bus use, while the H50 is for articulated and suburban coaches, similar in size and application to the B400 and B500 Bus Series transmissions, respectively. The H40 has a continuous input capacity of 280 hp (210 kW) and 910 lb⋅ft (1,230 N⋅m) of torque, while

5100-436: The stator from counter-rotating with respect to the prime mover but allows forward rotation. Modifications to the basic three element design have been periodically incorporated, especially in applications where higher than normal torque multiplication is required. Most commonly, these have taken the form of multiple turbines and stators, each set being designed to produce differing amounts of torque multiplication. For example,

5175-427: The torque converter must be carefully matched to the torque curve of the power source and the intended application. Changing the blade geometry of the stator and/or turbine will change the torque-stall characteristics, as well as the overall efficiency of the unit. For example, drag racing automatic transmissions often use converters modified to produce high stall speeds to improve off-the-line torque, and to get into

5250-475: The torque converter reduce efficiency and generate waste heat. In modern automotive applications, this problem is commonly avoided by use of a lock-up clutch that physically links the impeller and turbine, effectively changing the converter into a purely mechanical coupling. The result is no slippage, and virtually no power loss. The first automotive application of the lock-up principle was Packard 's Ultramatic transmission, introduced in 1949, which locked up

5325-719: The transmission shaft input (from the engine) and output (to the rear axle). Development of the V-Drive transmission was led by Bob Schaefer, an emigrant from Germany who had joined GM in 1942 after helping to lead the Twin Disc Company, which was one of the licensees of the Ljungstroms hydraulic torque converter. Schaefer was reassigned from the Detroit Transmission Division to Allison in 1946. The first production V-Drive transmissions were delivered in October 1947, with

5400-428: The turbine will gradually decrease, causing pressure on the stator to likewise decrease. Once in the coupling phase, the returning fluid will reverse direction and now rotate in the direction of the impeller and turbine, an effect which will attempt to forward-rotate the stator. At this point, the stator clutch will release and the impeller, turbine and stator will all (more or less) turn as a unit. Unavoidably, some of

5475-477: Was designed to be a drop-in replacement for existing axles for medium- and heavy-duty trucks and buses, allowing more flexibility in battery placement. The model designations for off-highway transmissions marketed under the Powershift TORQMATIC brand were in the format AAAA   1234 , where: Series indicates relative size and weight, with higher numbers assigned to larger transmissions. For example,

5550-568: Was the major factor in General Motors decision to buy the company following James Allison's death in 1928. Shortly after the sale to General Motors on April 1, 1929, Allison engineers began work on a 12-cylinder engine to replace the aging Liberty engines. The result was the V1710 12-cylinder aircraft engine and it made the company, renamed to the Allison Division of GM in 1934, also known as

5625-484: Was to vary the amount of torque multiplication produced by the converter. At the normal angle of attack, the stator caused the converter to produce a moderate amount of multiplication but with a higher level of efficiency. If the driver abruptly opened the throttle, a valve would switch the stator pitch to a different angle of attack, increasing torque multiplication at the expense of efficiency. Some torque converters use multiple stators and/or multiple turbines to provide

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