DOG AND SPLINE CLUTCH
The “dog” is a device or tool used to lock two components in relation to each other. Dog clutch is used to lock two shafts together or to lock gear to a shaft.
It consists of the sleeve having two sets of internal splines. It slides on a splined main shaft with a smaller diameter of splines. The bigger diameter splines match with the external dog clutch teeth on the driving shaft. When the sleeve is moved to slide on the splined shaft, then its teeth match with the dog clutches external teeth of the driving shaft. Thus, the sleeve rotates the splined shaft with the driving shaft. The clutch is said to be engaged. To disengage the dog clutch, the sleeve is moved back on the splined main shaft to have no contact with the driving shaft.
This clutch has no tendency to slip. The driven shaft revolves exactly at the same speed as that of the driving shaft, as soon as the clutch is engaged. Therefore, it is known as a positive clutch.
Watch the video below for better understanding about dog clutches.
Dog Clutch Operation
A dog clutch is a type of clutch which couples two rotating shafts or other rotating components not by friction but only by interference. The two components of the clutch are designed such that one will push the other, causing both of them to rotate at the same speed and will never slip. Dog clutches are used where slip is unnecessary and/or the clutch is not required to control torque. Dog clutches are not affected by any wear like that of friction clutches.
Dog clutches are used inside manual transmissions to lock different gears to the rotating output and input shafts. A synchromesh the arrangement ensures smooth engagement by matching the shaft speeds before the dog clutches is allowed to engage. A good example of a dog clutches can be found in a Sturmey Archer bicycle hub gear where a sliding cross-shaped clutch is used to lock the driver assembly to the different parts of the planetary geartrain.
- No slip operation.
- Develop a very little amount of heat since they do not depend on friction.
- Generally, the dog clutch is lighter and less costly than a friction clutch of similar torque capacity.
- Cannot be engaged at high speeds.
- Shock accompanies engagement at any speed.
- When both the driving shaft and driven shafts are at rest, some relative motion required to engage.