Increasing power on an Electric Clutch

I rated you answer as good. (it would have been a VERY good answer if the box had been available!!).

yeah, that's the truth.

Your mower is not designed to cut those thicker bushes. If you want better efficiency, you should have bought a bigger mower rather than replacing the clutch. I think the mechanical clutch fails or slides because the load is heavy. Increasing the voltage of the electric clutch wouldn't inrease the frictional properties of he clutch.

Think Different: Approach the grass cutting job by raising cutting-deck. Drive slower. Let the sun remove the moisture in the cut grass. Go for your next (lower) cut. Also, check clutch for spring loaded adjustment bolts, to increase magnetic force between the clutch disks. Enjoy the sweet smell of cut grass!

I would also recommend against increasing the voltage. Not so much because of the ability of the electrics to handle the heat. More in the direction that the clutch is supposed to slip when under loads that are exceeding the limits of the machine. I am curious if you have tested the voltage at the clutch to make sure it is receiving what it is supposed to. Also you did not mention how tall or how thick the grass is. My wife routinely uses our mower as a Bush Hog. She cuts the lawn, tree roots, rocks, and anything else that gets in her way. I am also curious if you have made any changes to the mower that would increase the load on the clutch. Have you changed over to mulching blades? Are you trying to cut grass when the lawn is wet? Wet grass tends to load up under the deck not just plugging the discharge chute. Is there a chance that it is not the clutch? Could it be the drive belts or possibly a sheared key in the drive pulley? I have seen cases in machines where there was intermittent slippage due to increased loads. Under moderate loads (ie. shorter grass) it would operate as it should.

Steve,

What is the nominal engine power (I'm guessing ~30 hp)?

Is the mowing deck belt or shaft driven?

Is the problem excessive slipping during engagement or when the clutch is fully engaged and you transition from light to heavy load?

If the clutch is slipping under load, I suspect it is the belt that is slipping not the clutch. If the clutch is working properly it should take 200 ft-lbf of torque to make it slip once it's fully engaged. A 30 hp engine will have a peak torque of less than 50 ft-lbf. (rough numbers).

Sorry if I'm repeating The Mechanic's observations. He must have posted just before me.

What about some other mechanical problem that adds more load, such as a bearing beginning to seize?

How about sharpening the blade before each session of cutting overly heavy grass? sharp blades do cut really nice!

elnav

I talked to my brother last night. He owns a lawn and garden repair shop. He told me that the most common causes for the mower to not cut well are: driving to fast, grass to tall / thick (use a higher blade setting), wet grass, and the idler pulley pivot. I am assuming that you have had this mower a while so you know what it is capable of doing. If the problem came on gradually, or if it worked fine last fall and not now, then he said it is most likely the idler pulley pivot mechanism. These have very close tolerances and are prone to seizing. His routine for changing a clutch includes completely dismantling the idler pivot for a good cleaning and lube. The idler on this type of mower moves very little, so it can appear to work fine on short dry grass. He also mentioned a burnishing / break in procedure for the new clutch that you may not be aware of. With the engine at idle, turn the clutch on and off 3 to 4 times. Increase the RPM's to half of full throttle and repeat. Do this again at full speed. Until this is done the new clutch face is to smooth to grip well and will slip. Unless you have tested the old clutch to be sure it was defective, do not throw it away. He said more often then not the problem is not the clutch. Please let me know if this helps, so I can pass it along to him.

Thanks to all of you that have been kind enough to post your comments and advice. I will be giving the mower a full mechanical check out shortly and if it is just doing what it should then I will take the advice to cut higher. Can't unfortunately cut any slower as I'm already crawling at a snails pace.