A torque multiplier is a tool used to provide a mechanical advantage in applying torque to turn bolts, nuts or other items designed to be actuated by application of torque, particularly where there are relatively high torque requirements.
A torque multiplier is a tool used to provide a mechanical advantage in applying torque to turn bolts, nuts or other items designed to be actuated by application of torque, particularly where there are relatively high torque requirements.
Torque multipliers are often used instead of extended handles, often called "cheater bars". Extended handles use leverage instead of gear reduction to achieve torque. This torque is transmitted through the driving tool and could become dangerous in the case of a sudden catastrophic failure of the drive tool with the extended handle attached. Torque multipliers only have a fraction of the final torque pressure on the drive tool making them a safer choice.
Torque multipliers typically employ an epicyclic gear train having one or more stages. Each stage of gearing multiplies the torque applied. In epicyclic gear systems, torque is applied to the input gear or ‘sun’ gear. A number of planet gears are arranged around and engaged with this sun gear, and therefore rotate. The outside casing of the multiplier is also engaged with the planet gear teeth, but is prevented from rotating by means of a reaction arm, causing the planet gears to orbit around the sun gear. The planet gears are held in a ‘planet carrier' which also holds the output drive shaft. As the planet gears orbit around the sun gear, the carrier and the output shaft rotate together. Without the reaction arm to prevent rotation of the outer casing, the output shaft cannot apply torque. [1] [2]
Along with the multiplication of torque, there is a decrease in rotational speed of the output shaft compared to the input shaft. This decrease in speed is inversely proportional to the increase in torque. For example, a torque multiplier with a rating of 3:1 will turn its output shaft with three times the torque, but at one third the speed, of the input shaft. However, due to friction and other inefficiencies in the mechanism, the output torque is slightly lower than the theoretical output.
Torque multipliers are most often used when a compressed air powered impact wrench is unavailable due to remote locations without power, or where cost considerations require manually operated tools which do not require any power supply or power source of any kind. There are many instances where screws, bolts and other fasteners are secured so tightly that using a typical lug wrench with a cheater bar is not sufficient to loosen them. These include automotive repair, product assembly, construction projects, heavy equipment maintenance and other instances where high torque output is needed. A torque multiplier allows the user to generate high torque output without the use of an air compressor or impact gun.
A torque multiplier is generally used when there are space limitations that disallow the use of long handles. They are also used as a safer alternative to a cheater bar as lever length and operator effort are both reduced. Finally, torque multipliers allow for more accurate torque. By reducing the amount of effort needed to tighten, a torque multiplier allows for slow and smooth application, ensuring more accurate torque levels, and preventing damage to sensitive components. [3]
A coupling is a device used to connect two shafts together at their ends for the purpose of transmitting power. The primary purpose of couplings is to join two pieces of rotating equipment while permitting some degree of misalignment or end movement or both. In a more general context, a coupling can also be a mechanical device that serves to connect the ends of adjacent parts or objects. Couplings do not normally allow disconnection of shafts during operation, however there are torque-limiting couplings which can slip or disconnect when some torque limit is exceeded. Selection, installation and maintenance of couplings can lead to reduced maintenance time and maintenance cost.
A differential is a gear train with three drive shafts that has the property that the rotational speed of one shaft is the average of the speeds of the others. A common use of differentials is in motor vehicles, to allow the wheels at each end of a drive axle to rotate at different speeds while cornering. Other uses include clocks and analogue computers. Differentials can also provide a gear ratio between the input and output shafts. For example, many differentials in motor vehicles provide a gearing reduction by having fewer teeth on the pinion than the ring gear.
An epicyclic gear train is a gear reduction assembly consisting of two gears mounted so that the center of one gear revolves around the center of the other. A carrier connects the centers of the two gears and rotates, to carry the planet gear(s) around the sun gear. The planet and sun gears mesh so that their pitch circles roll without slip. If the sun gear is held fixed, then a point on the pitch circle of the planet gear traces an epicycloid curve.
A torque converter is a device, usually implemented as a type of fluid coupling, that transfers rotating power from 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.
Overdrive is the operation of an automobile cruising at sustained speed with reduced engine speed (rpm), leading to better fuel consumption, lower noise, and lower wear. The term is ambiguous. The most fundamental meaning is that of an overall gear ratio between engine and wheels, such that the car is over-geared, and cannot reach its potential top speed, i.e. the car could travel faster if it were in a lower gear, with the engine turning at higher RPM.
A manual transmission (MT), also known as manual gearbox, standard transmission, or stick shift, is a multi-speed motor vehicle transmission system where gear changes require the driver to manually select the gears by operating a gear stick and clutch.
A gear train or gear set is a machine element of a mechanical system formed by mounting two or more gears on a frame such that the teeth of the gears engage.
The sun and planet gear is a method of converting reciprocating motion to rotary motion and was used in the first rotative beam engines.
A cheater bar, snipe, or cheater pipe is an improvised breaker bar made from a length of pipe and a wrench (spanner).
The Rohloff Speedhub is an epicyclic internal hub gear for bicycles, developed and patented by Rohloff AG. It has been manufactured and marketed by that company since 1998. The Speedhub 500/14 has 14 equally spaced, sequential, non-overlapping gear ratios operated by a single twistgrip. The overall gear range is 526%, meaning the highest gear is 5.26 times as high as the lowest gear. Individual gear shifts when shifting up give an increase of about 13.6%.
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.
A cycloidal drive or cycloidal speed reducer is a mechanism for reducing the speed of an input shaft by a certain ratio. Cycloidal speed reducers are capable of relatively high ratios in compact sizes with very low backlash.
The 1000 series is a line of automatic transmissions for on-road trucks. All are 5 or 6-speed electronically controlled units and are manufactured by Allison Transmission in Indianapolis, Indiana as well as in Baltimore, Maryland and in Erskine, Minnesota.
A propeller speed reduction unit is a gearbox or a belt and pulley device used to reduce the output revolutions per minute (rpm) from the higher input rpm of the powerplant. This allows the use of small displacement internal combustion engines to turn aircraft propellers within an efficient speed range.
A torque limiter is an automatic device that protects mechanical equipment, or its work, from damage by mechanical overload. A torque limiter may limit the torque by slipping, or uncouple the load entirely. The action of a torque limiter is especially useful to limit any damage due to crash stops and jams.
British Railways 10100 was an unusual experimental diesel locomotive known informally as The Fell Diesel Locomotive. It was the joint production of Davey Paxman & Co, Shell Refining & Marketing Co and Lt-Col L. F. R. Fell, built for them by the London, Midland and Scottish Railway at Derby. Sir Harry Ricardo was also involved. By the time it emerged in 1950, nationalisation had taken place and it carried British Railways livery. The locomotive had six diesel engines, four of them used for traction. There were two auxiliary engines, both of which were 150 hp (110 kW) AEC 6-cylinder units, and these drove the pressure-chargers for the main engines and the purpose of this arrangement was to enable the main engines to deliver very high torque at low crankshaft speed.
An impact wrench is a socket wrench power tool designed to deliver high torque output with minimal exertion by the user, by storing energy in a rotating mass, then delivering it suddenly to the output shaft. It was invented by Robert H. Pott of Evansville, Indiana.
A breaker bar is a long non-ratcheting bar that is used with socket wrench-style sockets. They are used to break loose very tight fasteners because their additional length allows the same amount of force to generate significantly more torque than a standard length socket wrench. Their use prevents damage to the ratcheting mechanism of a socket wrench. Often, after the first half turn, the fastener is loose enough to be turned with a socket wrench.
The Ravigneaux gearset is a double planetary gear set, invented by Pol Ravigneaux, who filed a patent application on July 28, 1949, in Neuilly-sur-Seine France. This planetary gear set, commonly used in automatic transmissions, is constructed from two gear pairs, ring–planet and planet–planet. The gearset provides four forward gear ratios and reverse by braking or restraining various elements of the mechanism.
A battery torque wrench is a battery-operated torque wrench that can apply a specified torque without effort from the operator. It contains a planetary torque multiplier or a gearbox. A reaction device that absorbs the torque rather than the tool operator. The torque output is adjusted by varying the voltage on the motor. The battery torque wrench is used to remove stubborn nuts, or to apply accurate torque. The gearboxes can have multiplication ratios up to 125:1.