Stihl HT 75 Maintenance

[treefarmer]

I hope that Stilltech reads this post.

I have an HT 75 telescoping pruning saw that I use in the pine stand on the treefarm. The owner's manual describes a procedure for lubricating the driveshaft on the HT 70 (non-telescoping), but not the HT 75. This saw is about a year and a half old, as has probably been run for 150-200 hours. Do I need to perform regular maintenance to the shaft, or is imaint. only required on the HT 70 as the owner's manual suggests?

Good little saw, could use a little more power, especially when it's cold or fully extended.

 

[stihltech]

HT75

The shaft is a bear to take apart on the extended trimmer. That is why they do not say to do it. We only use WD 40 on the splines. I have had no problems with shaft lubrication.
As for the power, I think it would cause problems if it was higher. There is alot of lightweight shaft out there. To make it tougher would take a lot more money or add alot more weight. The secret is to keep the chain very sharp and let the saw do the cutting.
I will check my info today at work and ley you know if I find anything different.
As for the cold part, emissions motors are lean to begin with , and then we put all that shaft out there on a small motor. It just has to warm up a bit. Give it half choke until it revs for a few seconds, I find this helps on a cold start.

 

[treeclimber165]

I agree with stihltech. Used Stihl ht75's for years and never saw a shaft lubed. Saw many torn up, but only from abuse. Cutting too big of a limb with a dull chain can bugger up the splines from the twisting action on the shaft. That, and dropping it on the ground. New shafts run about $300 installed.
If the chain needs tensioning, STOP and SHARPEN IT! You shouldn't ever need to force it through a cut. If you let the sharp chain do the work, this unit will last a loooooong time.

 

[treefarmer]

Thanks for the advice guys. I assume to lube the splines I should loosen the cutterhead and slide it off the shaft to expose the splines? Would a heavier oil than WD-40 help to protect the splines from shear forces (say a thin coating of 75W-90)? Just a thought.

I realize this little engine has to overcome a lot of parasitic friction with all that shaft. It's little breathless, but I still think it's a great little saw - definitely beats using a pole pruner, especially with tendonis in the wrist and elbow.

Thanks again.

-Clark

 

[treeclimber165]

I don't believe the shaft needs much lube. Anything heavier than WD-40 will leave a residue which will get cruddy with dust and dirt. All that crud grinding in the grooves will probably negate any short-term benefits from the lube. I'd probably blow it clean and WD-40 it when it starts getting hard to extend or retract, but no more often than once per year. This is a non-maintenance item, but you can screw with it if you like.

 

[stihltech]

HT75

Be careful! When you take it apart things may go flying and not every stihltech will be able to get it back together correctly. I would not take it apart. No lube problems since they came out. Only twisted shafts due to abuse ( or driven over). I do about three a year. Lube has caused no failures.
Also, HT70 shaft uses bushings, HT75 uses bearings to support the shaft. That is the difference.

 

[treefarmer]

Evidently better left untouched

Based on the last two posts, I'm opting to leave it alone. Thanks again guys.