A jacking gear (also known as a turning gear) is a device placed on the main shaft of an engine or the rotor of a turbine. The jacking gear rotates the shaft or rotor and associated machinery (such as reduction gears and main steam or gas turbines), to ensure uniform cool-down. Without turning, hogging or sagging can occur. Additionally, the jacking gear's assistance in rotation can be used when inspecting the shaft, reduction gears, bearings, and turbines. As an auxiliary function, the jacking gear also helps to maintain a protective oil membrane at all shaft journal bearings.
Hogging is when the shaft bows upwards due to thermal stratification.
On the engine shaft of a marine vessel, this process also prevents the shaft from warping when a ship is preparing to achieve maneuvering status.
The jacking gear motor is generally designed to rotate the shaft at approximately 1/10 rpm. Most jacking gear motors are rated at 5hp. The jacking gear motor assembly applies power and torque to the reduction gear by a flexible coupling or clutch that can freely engage and disengage to the high-pressure pinion (driving gear). Engaging is accomplished by means of a simple lever. Some newer propulsion arrangements utilize an automatic control system located in the engine room. Jacking gears often feature a lock to prevent the shaft from turning during current or tide changes or when being towed.
But some industrial gas turbines (GE Frame 5 and Frame 6 types) use a jacking system in which two hydraulic cylinders rotates the shaft about 1/4 turn in one or two seconds every 30 seconds.
GE Frame 9B gas turbines, in which accessories were designed in beginning of 1970's by Alstom Belfort engineering, use a high pressure hydraulic motor which connects to the main shaft through an automatic SSS Clutch. Turning speed was chosen about 6 RPM, because the resisting torque is the smallest at this speed, then requiring a very low power.
A clutch is a mechanical device that allows an output shaft to be disconnected from a rotating input shaft. The clutch's input shaft is typically attached to a motor, while the clutch's output shaft is connected to the mechanism that does the work.
A starter is a device used to rotate (crank) an internal-combustion engine so as to initiate the engine's operation under its own power. Starters can be electric, pneumatic, or hydraulic. The starter can also be another internal-combustion engine in the case, for instance, of very large engines, or diesel engines in agricultural or excavation applications.
An automatic transmission is a multi-speed transmission used in motor vehicles that does not require any input from the driver to change forward gears under normal driving conditions. Vehicles with internal combustion engines, unlike electric vehicles, require the engine to operate in a narrow range of rates of rotation, requiring a gearbox, operated manually or automatically, to drive the wheels over a wide range of speeds.
A transmission 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.
A dynamometer or "dyno" is a device for simultaneously measuring the torque and rotational speed (RPM) of an engine, motor or other rotating prime mover so that its instantaneous power may be calculated, and usually displayed by the dynamometer itself as kW or bhp.
Hydramatic is an automatic transmission developed by both General Motors' Cadillac and Oldsmobile divisions. Introduced in 1939 for the 1940 model year vehicles, the Hydramatic was the first mass-produced fully-automatic transmission developed for passenger automobile use.
A pneumatic motor, or compressed-air engine, is a type of motor which does mechanical work by expanding compressed air. Pneumatic motors generally convert the compressed-air energy to mechanical work through either linear or rotary motion. Linear motion can come from either a diaphragm or piston actuator, while rotary motion is supplied by either a vane type air motor, piston air motor, air turbine or gear type motor.
A sprag clutch is a one-way freewheel clutch. It resembles a roller bearing but, instead of cylindrical rollers, non-revolving asymmetric figure-eight shaped sprags, or other elements allowing single direction rotation, are used. When the unit rotates in one direction the rollers slip or free-wheel, but when a torque is applied in the opposite direction, the sprags tilt slightly, producing a wedging action and binding because of friction.
A motor drive is a physical system that includes a motor. An adjustable speed motor drive is a system that includes a motor that has multiple operating speeds. A variable speed motor drive is a system that includes a motor that is continuously variable in speed. If the motor is generating electrical energy rather than using it, the motor drive could be called a generator drive but is often still referred to as a motor drive.
A fluid coupling or hydraulic coupling is a hydrodynamic or 'hydrokinetic' device used to transmit rotating mechanical power. It has been used in automobile transmissions as an alternative to a mechanical clutch. It also has widespread application in marine and industrial machine drives, where variable speed operation and controlled start-up without shock loading of the power transmission system is essential.
Overspeed is a condition in which an engine is allowed or forced to turn beyond its design limit. The consequences of running an engine too fast vary by engine type and model and depend upon several factors, the most important of which are the duration of the overspeed and the speed attained. With some engines, a momentary overspeed can result in greatly reduced engine life or catastrophic failure. The speed of an engine is typically measured in revolutions per minute (rpm).
A hydraulic motor is a mechanical actuator that converts hydraulic pressure and flow into torque and angular displacement (rotation). The hydraulic motor is the rotary counterpart of the hydraulic cylinder as a linear actuator. Most broadly, the category of devices called hydraulic motors has sometimes included those that run on hydropower but in today's terminology the name usually refers more specifically to motors that use hydraulic fluid as part of closed hydraulic circuits in modern hydraulic machinery.
The Turboglide is a Chevrolet constant torque, continuously variable automatic transmission first offered as an option on Chevrolet V8 passenger cars for 1957. It consisted of a turbine-driven planetary gearbox with a 'switch pitch' dual-pitch torque converter stator. It had a die-cast aluminum transmission case, like Packard's Ultramatic of 1956. Turboglide cost about $50 more than the Powerglide 2-speed automatic. It was available in all V8-powered 1957-1961 Chevrolet models except the Corvette. General Motors produced 646,000 of these transmissions during its production.
Turbo transmissions are hydrodynamic, multi-stage drive assemblies designed for rail vehicles using internal combustion engines. The first turbo-transmission was developed in 1932 by Voith in Heidenheim, Germany. Since then, improvements to turbo-transmissions have paralleled similar advances in diesel motors and today this combination plays a leading role worldwide, second only to the use of electrical drives.
This article briefly describes the components and systems found in jet engines.
The yaw bearing is the most crucial and cost intensive component of a yaw system found on modern horizontal axis wind turbines. The yaw bearing must cope with enormous static and dynamic loads and moments during the wind turbine operation, and provide smooth rotation characteristics for the orientation of the nacelle under all weather conditions. It has also to be corrosion and wear resistant and extremely long lasting. It should last for the service life of the wind turbine) while being cost effective.
A motorcycle transmission is a transmission created specifically for motorcycle applications. They may also be found in use on other light vehicles such as motor tricycles and quadbikes, go-karts, offroad buggies, auto rickshaws, mowers, and other utility vehicles, microcars, and even some superlight racing cars.
The accessory drive is a gearbox that forms part of a gas turbine engine. Although not part of the engine's core, it drives the accessories – such as generators, pumps for fuel and lubrication oil, air compressors, hydraulic pumps and engine starters – that are otherwise essential for the operation of the engine or the aircraft on which it is mounted. Accessory drives on large engines handle between 400–500 hp.
The Voith DIWA automotive engine was designed by Voith primarily for city-buses and suburban buses. The motor utilizes a Differential-Wandler (Converter) or DIWA which replaces two gears which would be used on a conventional transmission. Voith has designed many variations and generations of the Voith DIWA engine.
A free-turbine turboshaft is a form of turboshaft or turboprop gas turbine engine where the power is extracted from the exhaust stream of a gas turbine by an independent turbine, downstream of the gas turbine. The power turbine is not mechanically connected to the turbines that drive the compressors, hence the term "free", referring to the independence of the power output shaft. This is opposed to the power being extracted from the turbine/compressor shaft via a gearbox.