Pawl

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A ratchet and pawl mechanism Trinquete no watermark.png
A ratchet and pawl mechanism

A pawl is a mechanical component that engages with another component to prevent movement in one direction, or prevent movement altogether. It is a type of latch. It consists of a spring-loaded solid part that is pivoted at one end and engages the other component at a steep angle at the other end. Pawls are often tapered, being wide at the pivoting end and narrow at the engaging end.

Latch door fastener

A latch or catch is a type of mechanical fastener that joins two objects or surfaces while allowing for their regular separation. A latch typically engages another piece of hardware on the other mounting surface. Depending upon the type and design of the latch, this engaged bit of hardware may be known as a keeper or strike.

Applications

Ratchet 
A pawl is used in combination with a ratchet gear in socket wrenches, bicycle freehubs, winches, and many other applications. [1] [2]
Ladders 
Dogs and pawls are used on extension ladders to prevent the ladder sections from sliding relative to each other. [3]
Table saw 
Pawls are used on table saws to grip the workpiece and prevent kickback. [4]
Pawl brake assembly Pawl brake (English).png
Pawl brake assembly
Parking 
A parking pawl is a device fitted to the automatic transmission of motor vehicles to lock it up when the vehicle is parked and to prevent it from moving. [5]

Related Research Articles

Clutch machine element for rigid, elastic, movable or releasable connection of two shafts

A clutch is a mechanical device which engages and disengages power transmission especially from driving shaft to driven shaft.

Strowger switch

The Strowger switch is the first commercially successful electromechanical stepping switch telephone exchange system. It was developed by the Strowger Automatic Telephone Exchange Company founded in 1891 by Almon Brown Strowger. Because of its operational characteristics it is also known as a step-by-step (SXS) switch.

Winch device used to pull in or let out a rope or cable

A winch is a mechanical device that is used to pull in or let out or otherwise adjust the tension of a rope or wire rope. In its simplest form, it consists of a spool attached to a hand crank. Winches are the basis of such machines as tow trucks, steam shovels and elevators. More complex designs have gear assemblies and can be powered by electric, hydraulic, pneumatic or internal combustion drives. It might include a solenoid brake and/or a mechanical brake or ratchet and pawl which prevents it unwinding unless the pawl is retracted.

Automatic transmission type of motor vehicle transmission that can automatically change gear ratios as the vehicle moves

An automatic transmission, also called auto, self-shifting transmission, n-speed automatic, or AT, is a type of motor vehicle transmission that can automatically change gear ratios as the vehicle moves, freeing the driver from having to shift gears manually. Like other transmission systems on vehicles, it allows an internal combustion engine, best suited to run at a relatively high rotational speed, to provide a range of speed and torque outputs necessary for vehicular travel. The number of forward gear ratios is often expressed for manual transmissions as well.

Ratchet (device)

A ratchet is a mechanical device that allows continuous linear or rotary motion in only one direction while preventing motion in the opposite direction. Ratchets are widely used in machinery and tools. The word ratchet is also used informally to refer to a ratcheting socket wrench.

A continuously variable transmission (CVT), also known as a shiftless transmission, single-speed transmission, stepless transmission, pulley transmission, or, in case of motorcycles, a 'twist-and-go', is an automatic transmission that can change seamlessly through a continuous range of effective gear ratios. This contrasts with other mechanical transmissions that offer a fixed number of gear ratios. The flexibility of a CVT with suitable control may allow the input shaft to maintain a constant angular velocity even as the output speed varies.

Manual transmission type of transmission used in motor vehicle applications

A manual transmission, also known as a manual gearbox, a standard transmission or colloquially in some countries as a stick shift, is a type of transmission used in motor vehicle applications. It uses a driver-operated clutch, usually engaged and disengaged by a foot pedal or hand lever, for regulating torque transfer from the engine to the transmission; and a gear selector that can be operated by hand or foot.

Parking pawl

A parking pawl is a device fitted to a motor vehicle's automatic transmission in order for it to lock up the transmission. It is engaged when the transmission shift lever selector is placed in the Park position, which is always the first position in all cars sold in the United States since 1965 through SAE J915, and in most other vehicles worldwide.

Freewheel

In mechanical or automotive engineering, a freewheel or overrunning clutch is a device in a transmission that disengages the driveshaft from the driven shaft when the driven shaft rotates faster than the driveshaft. An overdrive is sometimes mistakenly called a freewheel, but is otherwise unrelated.

In electrical controls, a stepping switch or stepping relay, also known as a uniselector, is an electromechanical device that switches an input signal path to one of several possible output paths, directed by a train of electrical pulses.

Hydramatic

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.

Parking brake secondary automotive braking system

In road vehicles, the parking brake, also called hand brake, emergency brake, or e-brake, is used to keep the vehicle stationary and in many cases also perform an emergency stop. Parking brakes on older vehicles often consist of a cable connected to two wheel brakes at one end and the other end to a pulling mechanism which is operated with the driver's hand or foot. The mechanism may be a hand-operated lever, at floor level beside the driver, or a straight pull handle located near the steering column, or a (foot-operated) pedal located beside the drivers leg. In most automobiles the parking brake operates only on the rear wheels, which have reduced traction while braking. Some automobiles have the parking brake operate on the front wheels, for example most Citroens manufactured since the end of World War II, and the early models of the Saab 900.

The AXOD was a 4-speed automatic transaxle for transverse front wheel drive automobiles from the Ford Motor Company. It was introduced in the 1986 Ford Taurus/Mercury Sable. The AXOD and its successors are built in Ford's Van Dyke Transmission plant in Sterling Heights, Michigan. Production of the final member of the family, the 4F50N, ended in November 2006.

In horology, a maintaining power is a mechanism for keeping a clock or watch going while it is being wound.

Gear stick

A gear stick, gear lever, gearshift or shifter is a metal lever attached to the shift assembly in a manual transmission-equipped automobile and is used to change gears. In an automatic transmission-equipped vehicle, a similar device is known as a gear selector. A gear stick will normally be used to change gear whilst depressing the clutch pedal with the left foot to disengage the engine from the drivetrain and wheels. Automatic transmission vehicles, semi-automatic transmissions, and those with continuously variable transmission gearboxes do not require a clutch pedal.

M19 Tank Transporter

The M19 Tank Transporter was a heavy tank transporter system used in World War II and into the 1950s. It consisted of a 12-ton 6x4 M20 Diamond T Model 980 truck and companion 12-wheel M9 trailer.

Meillerwagen

The Meillerwagen was a German World War II trailer used to transport a V-2 rocket from the 'transloading point' of the Technical Troop Area to the 'launching point', to erect the missile on the Brennstand, and to act as the service gantry for fuelling and launch preparation.

In engineering, a dog is a tool or part of a tool that prevents movement or imparts movement by offering physical obstruction or engagement of some kind. It may hold another object in place by blocking it, clamping it, or otherwise obstructing its movement. Or it may couple various parts together so that they move in unison – the primary example of this being a flexible drive to mate two shafts in order to transmit torque. Some devices use dog clutches to lock together two spinning components. In a manual transmission, the dog clutches, or "dogs" lock the selected gear to the shaft it rotates on. Unless the dog is engaged, the gear will simply freewheel on the shaft.

A park by wire system engages the parking pawl of a transmission using electrical means. This can also be considered as part of a shift by wire system whose objective is to put the vehicle in Park, Reverse, Neutral and Drive modes without the traditional mechanical system which involves linkages between the gear shifter and the transmission. The main components of a park by wire system include the driver interface which could be a lever, switch or knob as designed by the OEM (input), an electronic control unit to host the control system and actuators which are capable of driving the parking pawl into and out of the locking position with the parking gear of the transmission.

References

  1. Nitaigour Premcahnd Mahalik, Mechatronics: Principles, Concepts and Applications, p. 271, Tata McGraw-Hill Education, 2003 ISBN   0070483744.
  2. Richard Krolak, Cruising World, "Servicing your winches", April 1990, pp. 107-108
  3. International Association of Fire Chiefs, Fundamentals of Fire Fighter Skills, p. 363, Jones & Bartlett Publishers, 2012 ISBN   1449666507.
  4. Table Saw Techniques: Use Your Saw Like a Pro, p. 12, Quarto Publishing Group USA, 2003 ISBN   1610602951.
  5. Keith Santini, Kirk Vangelder, Automotive Automatic Transmissions and Transaxles, p. 174, Jones & Bartlett Learning, 2017 ISBN   1284122034.