Dog Clutch issues can be a common problem for boat owners. However, by keeping this component of your boat well maintained and correctly adjusted, you can enjoy trouble free time on the water.
The Dog Clutch uses interference to couple two rotating shafts, and functions by mating a set of teeth on one half of the clutch mechanism to a set of identical recesses on the other.
This allows both shafts to turn at the same speed without slipping and with minimal clutch wear.
Dog clutches can’t be used to control torque like a friction clutch, as the two parts of a Dog Clutch are designed so that one will push the other and both will rotate at same speed and not slip.
When the two clutch plates are brought together, they create an effective join between the two shafts and transfer the rotational motion from the engine to the prop.
Because the gears are always rotating, when shifting occurs the dog clutch will be subject to wear, so to help maximise the life of your Dog Clutch, here are some simple rules to follow when shifting.
You should always try to shift gear at the lowest possible speed, when the engine is at idle or the boat is stationary.
It is recommended to shift into gear quickly, as slowly shifting gear causes the dog teeth to rattle across the drive gear teeth. By shifting quickly, the teeth should only come into contact once during each shift and helps to minimise wear.
Don’t try and shift gear when the engine not running. As the Dog Clutch and gear teeth meet end on, any undue force on the linkages can cause them to bend, which can then create gear jumping problems as the bent linkages will cause the Dog Clutch to not engaged correctly.
Regularly have the shift system checked and adjusted to ensure the Dog Clutch is moving correctly with full engagement. Worn cables or linkages that reduce Dog Clutch travel can result in gear jumping under load which will quickly wear the faces of the Dog Clutch teeth.
This can also cause a hammer blow movement and forces through the rest of the transmission.
Regular inspections of shifting fork wear should also be made, as worn forks can create unwanted movement, gear shifting problems, and may brake under load.
When a Dog Clutch is fully engaged, there should be no pressure against the forks. The shifting fork is there only to shift into gear and not to hold the drive train in gear. So, any pressure at this point will wear the fork prematurely.
Usually, you will notice the first signs of a worn Dog Clutch when backing off from speed. A common fault here is that the clutch will drop out into neutral.
If you’re experiencing issues with your shifting or Dog Clutch, give our service team a call and arrange for an inspection or service.