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Brands, Models & Vintage Know-HowWhy Some Tractors Have Two Clutches
If you have climbed onto an older tractor and found two pedals or a pedal and a lever for the clutch, you are looking at a design meant to keep the PTO and the wheels under separate control.
Key points
- Dual clutches separate wheel drive from PTO drive
- A live PTO keeps turning when you stop the tractor
- Learn the pedal stages before working with an implement
- Shut down the engine and wait for all motion to stop before clearing a jam
- Clutch replacement is a job for a qualified mechanic
Why would a tractor have two clutches?
The reason is the PTO. On a simple single-clutch tractor, pressing the clutch pedal disconnects the engine from both the transmission and the PTO. If you are running a baler or a mower, the implement stops the moment you push the pedal, and so does any momentum it was carrying.
A two-stage or dual clutch lets you separate those functions. The first stage disconnects the drive to the wheels, and the second stage disconnects the PTO. That lets the implement keep running while you stop or shift, which is the idea behind what is often called a live PTO.
On a vintage tractor, the PTO clutch may be a hand lever beside the seat rather than a second pedal, so look for a lever, a pedal or a two-position pedal before you assume anything.
How does a dual-stage clutch work in practice?
On many tractors with this arrangement, pressing the pedal part way disengages the wheels, and pressing it all the way down also disengages the PTO. Others use a separate lever or control for the PTO. The details differ by make and model, so the operator's manual for your tractor is the authority.
Practice in an open area before you work with an implement. Learn the point where the first stage lets go and the second begins, so that you can stop the tractor without cutting the PTO unless you intend to.
- Read the manual's clutch and PTO section first
- Practice with the PTO off and no implement attached
- Learn the feel of the first stage versus full travel
- Never reach near the PTO while it is turning
What is the difference between a live PTO and a transmission-driven PTO?
A live PTO takes power directly from the engine, independent of the transmission clutch. It keeps turning when the tractor stops moving. A transmission-driven PTO stops when you push the clutch, and its speed is tied to how the transmission is engaged.
Each has advantages. Live PTO makes it easier to run balers, mowers and spreaders through starts and stops. A transmission-driven system is simpler. Know which one you have, since it changes how you handle a plugged implement.
What safety points matter with PTO and clutch?
A PTO shaft turning at 540 or 1000 rpm can wrap clothing and pull a person in within a moment. Keep shields in place, never step over a turning shaft and shut off the PTO and the engine before you clear a jam or adjust anything.
Do not rely on the clutch alone as a lockout. Stop the engine, remove the key where appropriate, wait for all movement to stop and follow the manufacturer's instructions. Never remove or bypass a shield or interlock. OSHA, NIOSH and your extension office publish PTO safety guidance.
What problems show up with dual clutches?
Common signs of trouble are slipping under load, a pedal that has little free play or too much, grabbing, noise when the pedal is pressed and a PTO that will not disengage. Oil leaks from the rear of the engine or the front of the transmission can foul clutch parts.
Free play adjustment is described in the manual for many models. Beyond simple adjustment, clutch work usually means splitting the tractor, which is a job for a qualified mechanic or the dealer service department.
How do you get the most life from the clutch?
Do not ride the pedal. Resting your foot on it wears the release bearing and can cause slipping. Start loads smoothly, engage the PTO at low engine speed for large implements and avoid slipping the clutch to hold the tractor on a slope.
Keep up with any greasing the manual calls for and fix leaks promptly. A 30-acre hay operation running a baler in heat will thank you for a clutch that is in good order.
Should you buy a tractor with this design?
Many people prefer a live PTO for hay work and similar jobs. Ask the seller to demonstrate both the wheel clutch and the PTO and watch for slipping or noises. If you are not sure what you are looking at, have a mechanic check it.
Compare the cost of clutch repair, which is usually significant, against the price difference between tractors. Ask for service records and any history of clutch work.
If the tractor has been used hard on a baler or a stump grinder, the PTO side of the clutch may be worn even if the wheel side feels fine, so test both separately.
Sources and further reading
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