What is an overrunning clutch on a tractor?
An overrunning PTO clutch is a device that allows a tractor’s power take-off (PTO) shaft to be driven in one direction, but to spin freely (freewheel) in the other direction. The frewheel action of the overrunning clutch prevent equipment from “driving” the tractor through its PTO shaft.
Why is an overrunning clutch needed?
An overrunning clutch transmits torque in one direction only and permits the driven shaft of a machine to freewheel, or keep on rotating when the driver is stopped. On bicycles, such clutches permit the rider to coast without moving the pedals.
What are the three types of overrunning clutches?
Most overrunning clutches are one of three types: roller ramp, sprag, or wrap spring. A relatively new device, called the wedge ramp clutch, incorporates the major benefits of these well-established types.
How does a PTO overrun clutch work?
This overrunning clutch allows the PTO shaft to rotate in one direction, but also to spin freely the opposite way. This works to control the speed of the implement that is being hauled behind the tractor. By doing so, the implement does not exceed the tractor’s speed when the tractor is slowing down.
Which is used to operate the overrunning clutch drive pinion?
When the engine starts and is running under its own power, the ring gear attempts to drive the pinion gear faster than the starter motor. This unloads the clutch rollers and releases the pinion gear to rotate freely around the armature shaft.
What is a PTO slip clutch?
A PTO slip clutch is a torque limiting device that, when overcome with too much torque, limits the amount of torque being transferred from the tractor to the implement. This is accomplished by, you guessed it, slipping or spinning free which allows the two sides of the PTO shaft to spin at different speeds.
Where is the overrunning clutch located?
A freewheeling unit commonly consists of a one-way sprag clutch, located between the engine and main rotor transmission. Usually you find this sprag clutch either in the upper pulley (piston helicopter) or mounted on the engine gearbox (turbine helicopter).
What is a 2 stage clutch on a tractor?
Any tractor that has a power takeoff assembly generally has a two-stage clutch. A two-stage clutch allows you to engage the clutch to change gears without disengaging the PTO drive. The mower or other machinery operated by your PTO will disengage only when the clutch is pressed completely down.
Does a direct drive starter need an overrunning clutch?
What is the purpose of the overrunning clutch in the starter drive? The starter motor converts: electrical energy into mechanical energy. Technician A says that the direct drive starter doesn’t need an overrunning clutch on its starter drive because it is continuously meshed with the flywheel.
What would happen if the starting motor did not have an overrunning clutch?
The ratio of the number of teeth on the ring gear and the starter drive pinion gear is usually between 15:1 and 20:1. This would destroy the starter motor if it was not disengaged from the engine. Overrunning Clutch Drive. The most common type of starter drive is the overrunning clutch.
Which is better slip clutch or shear bolt?
You need to keep a good supply of shear bolts to hand when using your machinery. Whereas the PTO slip clutch allows for the drive to be stopped when needed and resume the torque when free of any obstructions. This avoids too much interference when working and removes the need to be changing pins several times a day.