Clutch Maintenance On Pro Saws

Most pro saw users in the Northwestern US have problems with the clutches on their pro saws at some point during the saw's life. On a saw with many hours of use, having a clutch wear out is expected, but sometimes pro users experience premature clutch failure, and this can be frustrating. 

With some exceptions, premature clutch failure can be attributed to long bars and chains fitted on saws used in the Northwest. These long cutting attachments require more clutch "slip." Over time this causes excessive wear on the friction surfaces of the clutch shoes and drum.

One thing that would really help is if pro saws came with larger clutches. Unfortunately, saw manufacturers are reluctant to put bigger clutches on their saws because this would make the saws heavier. Northwest professionals have a long history of demanding high power to weight powerheads. Besides, the rest of the world wouldn't benefit much from a larger clutch. The rest of the world fits short bars on these same powerheads, so for them a small light clutch works best. 

While larger clutches would give a longer service life for many Northwest pros,  it is also true that today's  saws can manage quite well with the clutches they have if they are maintained and replaced when worn. Unfortunately, clutches are one of the components pro users don't think to service.

Broken Clutch Springs

Have you ever had trouble keeping clutch springs in your saw? Almost everyone has at one time or another. After your clutch locks up for the third  time, you start to wonder why springs aren't holding up. You wonder why the manufacturer can't improve this weak part. While you are cussing the springs, more times than not, better quality springs is not the solution. The problem  is wear in the drum and shoes. Broken springs are just a consequence of it.

When the clutch wears, the surface of the shoes wear. The inside of the clutch drum also wears. After awhile, the shoes must travel much farther before they contact the surface of the drum. This extra travel can stretch springs beyond their limits. Sometimes the holes in the shoes where the springs are attached also wear. The spring tail actually starts to sink into the shoe material. In both cases, the clutch seizes when the springs break, but the problem is really caused by other worn parts.

When inspecting a clutch, check for wear described above. Also check where the shoes slide on the spider and any guides if the clutch uses them. When you find excess wear on the shoes, springs and spider consider replacing the whole clutch assembly. Have a look at the clutch drum, too. If you see wear below the surface where the shoes contact the drum, this part should also be changed. 

Lubricating The Clutch Bearing

Another thing many pro users forget to do is lube the clutch bearing. This small needle bearing is mounted between the clutch hub and crankshaft. When you are cutting with the saw, the bearing does not turn. When you idle the motor, it is what allows the chain to stop while the engine still turns. On most models, it gets a little lubrication from bar and chain oil that drips down from the sprocket, but this is not enough. For this bearing to give a long service life, it needs occasional grease applied to it in the shop or by the operator.

While the bearing itself is not an expensive part, nor is it expensive to replace, it runs on the end of the crankshaft. If this bearing is allowed to fail, it may damage the surface on the crankshaft. Once this surface is damaged, even a new bearing won't last, so the crank has to be replaced. This is an expensive repair and can be completely avoided with a little grease and some routine maintenance.

This information should help you get maximum performance from the clutch on your pro saw. Keeping the clutch parts fresh and some simple routine service, will eliminate down time and the frustration that goes with it. If you need information or have questions about a clutch problem you are experiencing on your pro saw, please contact us.

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