The General Electric T64 is a free-turbine turboshaft engine that was originally developed for use on helicopters , but which was later used on fixed-wing aircraft as well. General Electric introduced the engine in 1964. The original engine design included technical innovations such as corrosion resistant and high-temperature coatings. The engine features a high overall pressure ratio , yielding a low specific fuel consumption for its time. Although the compressor is all-axial, like the earlier General Electric T58 , the power turbine shaft is coaxial with the HP shaft and delivers power to the front of the engine, not rearwards. Fourteen compressor stages are required to deliver the required overall pressure ratio. Compressor handling is facilitated by 4 rows of variable stators . Unlike the T58, the power turbine has 2 stages.
22-565: Later versions of the engine produce from 3,925 to 4,750 shp (2,927 to 3,542 kW). The engine was designed to accommodate different gearboxes or shaft drives, for helicopter or turboprop fixed-wing applications. The engine could be operated continuously at angles between 100 degrees upward and 45 degrees downward for STOL or helicopter applications. Data from: Vectorsite;Sikorsky Giant Helicopters Data from Gas Turbine Engines Comparable engines Related lists Transmission (mechanics) A transmission (also called
44-452: A crash gearbox , is a form of manual transmission based on gears that do not use synchronizing mechanisms . They require the driver to manually synchronize the transmission's input speed (engine RPM) and output speed (driveshaft speed). Non-synchronous transmissions are found primarily in various types of industrial machinery ; such as tractors and semi-tractors . Non-synchronous manual transmissions are also found on motorcycles , in
66-431: A gearbox ) is a mechanical device which uses a gear set —two or more gears working together—to change the speed, direction of rotation, or torque multiplication/reduction in a machine . Transmissions can have a single fixed-gear ratio, multiple distinct gear ratios , or continuously variable ratios. Variable-ratio transmissions are used in all sorts of machinery, especially vehicles. Early transmissions included
88-513: A fixed ratio to provide either a gear reduction or increase in speed, sometimes in conjunction with a change in the orientation of the output shaft. Examples of such transmissions are used in helicopters and wind turbines . In the case of a wind turbine, the first stage of the gearbox is usually a planetary gear, to minimize the size while withstanding the high torque inputs from the turbine. Many transmissions – especially for transportation applications – have multiple gears that are used to change
110-475: Is connected to the engine via a torque converter (or a fluid coupling prior to the 1960s), instead of the friction clutch used by most manual transmissions and dual-clutch transmissions. A dual-clutch transmission (DCT) uses two separate clutches for odd and even gear sets . The design is often similar to two separate manual transmissions with their respective clutches contained within one housing, and working as one unit. In car and truck applications,
132-446: Is usually activated by pressing the clutch pedal all the way to the floor or pressing a button on the top of the gear lever. The purpose of the clutch brake is to slow down (or stop) the rotation of the transmission's input shaft, which assists in shifting the transmission into neutral or first gear when the vehicle is at a standstill. The clutch brake not only slows or stops the idle gear axis but can also prevent shifting into gear until
154-454: The DCT functions as an automatic transmission, requiring no driver input to change gears. A continuously variable transmission (CVT) can change seamlessly through a continuous range of gear ratios . This contrasts with other transmissions that provide a limited number of gear ratios in fixed steps. The flexibility of a CVT with suitable control may allow the engine to operate at a constant RPM while
176-457: The clutch and/or shift between gears. Many early versions of these transmissions were semi-automatic in operation, such as Autostick , which automatically control only the clutch , but still require the driver's input to initiate gear changes. Some of these systems are also referred to as clutchless manual systems. Modern versions of these systems that are fully automatic in operation, such as Selespeed and Easytronic , can control both
198-401: The clutch operation and the gear shifts automatically, without any input from the driver. An automatic transmission does not require any input from the driver to change forward gears under normal driving conditions. The most common design of automatic transmissions is the hydraulic automatic, which typically uses planetary gearsets that are operated using hydraulics . The transmission
220-664: The clutch pedal is released a few centimetres (or inches) off the floor. In order to shift into gear, the clutch must be halfway off the floor, otherwise, the clutch brake will prevent the transmission from being shifted into or out of gear. Any transmission that requires the driver to manually synchronize the engine speed with the speed of the driveshaft is non-synchronous. Non-synchronous transmissions are mostly used in semi-trucks, large industrial machines, older agricultural tractors (e. g. Massey Ferguson 135 ) and power take-offs . Sequential manual transmissions , which are commonly used in motorcycles , ATVs , and racecars , are
242-412: The driver to selecting either the next or previous gear, in a successive order. A semi-automatic transmission is where some of the operation is automated (often the actuation of the clutch), but the driver's input is required to move off from a standstill or to change gears. An automated manual transmission (AMT) is essentially a conventional manual transmission that uses automatic actuation to operate
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#1732849068441264-469: The early mass-produced automobiles, the standard transmission design was manual : the combination of gears was selected by the driver through a lever (the gear stick ) that displaced gears and gear groups along their axes. Starting in 1939, cars using various types of automatic transmission became available in the US market. These vehicles used the engine's own power to change the effective gear ratio depending on
286-406: The engine within its power band to produce optimal power, fuel efficiency , and smooth operation. Multiple gear ratios are also needed to provide sufficient acceleration and velocity for safe & reliable operation at modern highway speeds. ICEs typically operate over a range of approximately 600–7000 rpm, while the vehicle's speeds requires the wheels to rotate in the range of 0–1800 rpm. In
308-478: The form of constant-mesh sequential manual transmissions . Prior to the 1950s and 1960s, most cars used constant-mesh (and also sliding-mesh) but non-synchronous transmissions. Most early automobiles were rear-engined, using a single-speed transmission and belt-drive to power the rear wheels. In 1891, the French Panhard et Levassor automobile used a three-speed manual transmission and is considered to have set
330-493: The load so as to keep the engine running close to its optimal rotation speed. Automatic transmissions now are used in more than 2/3 of cars globally, and on almost all new cars in the US. Most currently-produced passenger cars with gasoline or diesel engines use transmissions with 4–10 forward gear ratios (also called speeds) and one reverse gear ratio. Electric vehicles typically use a fixed-gear or two-speed transmission with no reverse gear ratio. The simplest transmissions used
352-449: The ratio of input speed (e.g. engine rpm) to the output speed (e.g. the speed of a car) as required for a given situation. Gear (ratio) selection can be manual, semi-automatic, or automatic. A manual transmission requires the driver to manually select the gears by operating a gear stick and clutch (which is usually a foot pedal for cars or a hand lever for motorcycles). Most transmissions in modern cars use synchromesh to synchronise
374-482: The right-angle drives and other gearing in windmills , horse -powered devices, and steam -powered devices. Applications of these devices included pumps , mills and hoists . Bicycles traditionally have used hub gear or Derailleur gear transmissions, but there are other more recent design innovations. Since the torque and power output of an internal combustion engine varies with its rpm , automobiles powered by ICEs require multiple gear ratios to keep
396-418: The speeds of the input and output shafts. However, prior to the 1950s, most cars used non-synchronous transmissions . A sequential manual transmission is a type of non-synchronous transmission used mostly for motorcycles and racing cars. It produces faster shift times than synchronized manual transmissions, through the use of dog clutches rather than synchromesh. Sequential manual transmissions also restrict
418-414: The techniques listed below. If improperly implemented, these techniques can cause damage to the vehicle or the loss of control of the vehicle. In big rigs and semi-trucks, the driver may have to complete 24 or more gear changes when accelerating from a standstill to 70 mph (110 km/h). Unlike any other type of transmission, non-synchronous transmissions often have a clutch brake mechanism, which
440-495: The template for multi-speed manual transmissions in motor vehicles. This transmission used a sliding-gear design without any form of speed synchronization, causing frequent grinding of the gear teeth during gear shifts. The Panhard design was refined over the years by other manufacturers to include "constant-mesh" gears (instead of sliding gears). The first usage of synchromesh was by Cadillac in 1928. Trained drivers of vehicles with non-synchronous transmissions sometimes use
462-572: The vehicle is engaged in lower gears. The design life of the lower ratio gears is shorter, so cheaper gears may be used, which tend to generate more noise due to smaller overlap ratio and a lower mesh stiffness etc. than the helical gears used for the high ratios. This fact has been used to analyze vehicle-generated sound since the late 1960s, and has been incorporated into the simulation of urban roadway noise and corresponding design of urban noise barriers along roadways. Non-synchronous transmission A non-synchronous transmission , also called
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#1732849068441484-452: The vehicle moves at varying speeds. CVTs are used in cars, tractors, side-by-sides , motor scooters, snowmobiles , bicycles, and earthmoving equipment . The most common type of CVT uses two pulleys connected by a belt or chain ; however, several other designs have also been used at times. Gearboxes are often a major source of noise and vibration in vehicles and stationary machinery. Higher sound levels are generally emitted when
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