Is a high level of vibration for a 'long hedge trimmer' normal?

[greenant88]

Hi first time poster, long time lurker!

 

I wanted to ask: Is it normal to use a 'long reach' petrol hedge cutter for only a few minutes and the vibrations be so strong that your arms hurt and feel numb? Normal in the sense of thats just how they work.

 

Yesterday I took the leap and bought a second hand Stihl KM 56 RC (the combi engine) with the HL-KM 145° KombiTool (long reach hedge cutter) which was in excellent condition.

 

I have previously used both regular and heavier duty 'normal' length Stihl hedge cutters  (like the HS 82 RC) belonging to other people and never noticed the vibrations before even after 30+ minutes.

 

Today I used it for the first time for a maximum of 5 minutes and I thought my arms were going to fall off afterwards! I realise that the light weight nature of this tool vs the 'standard' stockier one would increase the vibrations (the specs say ~8m/s vibrations for long vs ~3m/s for the normal length cutters) - but the test run makes me want put in on facebook for a loss and call it quits before using it again.

 

Any thoughts much appreciated.

 

Thank you

Edited November 9, 2022 by greenant88

[Mick Dempsey]

No. That doesn’t sound right.

[swinny]

Check head for grease this may contribute a little vibration. 

 

I never use the split shaft ones but I had bad vibe on one hedge trimmer die to a bent pole / shaft. Too much using it top of hedges and putting weight on it. 

 

Make sure nothings bent

[greenant88]

Thanks for both of your replies.

 

I'll have a check about if its properly greased and if its all straight - then invest in it a bit more sending it to the mechanic to check it out if necessary. I am hopeful as otherwise its perfect (low weight, can fit in the car disassembled). 

 

[Bolt]

33 minutes ago, swinny said:

 

I never use the split shaft ones but I had bad vibe on one hedge trimmer die to a bent pole / shaft. Too much using it top of hedges and putting weight on it. 

 

Make sure nothings bent

You shouldn’t be getting ‘painful’ levels of vibration on modern-ish tools.

 

Swinny’s suggested of bent drive shafts seems the most likely culprit.

 

The outer shaft may look fine, it’s the drive ‘rod’ running down the middle of the shafts that can be the problem.

 

Can you tell if the vibration seems worse if the thing is under load?

[greenant88]

Hi thank you for the reply. I can say from my observations:

 

-Starting it up: leaving it idling on the the ground its 'jumping' around

-Under load it seems less jumpy and more sustained, the same high vibration levels but faster. Under load I didn't notice it being more comfortable to use I believe, just more sustained.

 

I was so surprised by the level of vibration that at the job I just tried to get it over with. Sitting at home 4 hours later and my wrist is beginning to feel sore - im glad that it ran out of fuel after 5 minutes now!

 

Im wondering now that theres something wrong - when I collected it I didnt meet the seller rather his wife, and I noticed it jumping around on the floor initally. I figured it was because its so light. 2 hours in the car can make you believe whatever you want. I sent him a message on ebay and will see if he can confirm this. I did get it for a good price.

 

 

 

[Bolt]

Doesn’t sound right.

 

Have you tried the engine without the hedge trimmer attached?

[greenant88]

No  - if its ok without an attachment that would mean its the attachement that has a bent shaft?

 

I will try that tomorrow. If it is the attachement and its obvious then I can explain to the seller. Then I won't need a mechanic (unless I try and see if he'll fix the attachement).

 

Thank you very much and good thinking about trying it without the attachment. Makes total sense now to try it.

 

 

Edited November 9, 2022 by greenant88

[Ferguson system]

Like have been previously mentioned, check that the gear and joints have enough grease. Check that the knives does not have play (can be tightened, but make sure not to overtighten). They can clack and vibrate as the head becomes worn after much use. I usually use spray lubrication (thin penetrating oil, not sticky oil/grease) on the knives at the start of the workday and reapply when I refuel. Combi tools typically vibrate more than dedicated tools and it's easier to bend the shaft. Especially when changing between tools.

[adw]

If it’s  vibrating badly at idle then it is nothing to do with the gearbox or shaft as these are not moving at idle, so maybe imbalance in the centrifugal clutch?