Tanaka Hedge Trimmer

[Derekl]

Hi, I have a Tanaka hedge trimmer that has been perfect for a few years, recently when using it for a while the blades stop moving. The engine is running, however when I look to accelerate the blades stall. The machine starts and runs perfectly when cold, however if I stop and restart then the blades will not move. I am happy that the blades are not stuck or trapped as they remain free. Does anybody have a suggestion as how to resolve this problem. 
 

Many thanks,

 

Derekl

[woody paul]

Is it a long reach one. 

[spudulike]

If it is a not a pole trimmer, I am not sure how you know the blades are free unless I guess you push the teeth together and they move.

It could be a sheared clutch, if it is, the engine will rev up freely and the blades won't move.

It could be the clutch has rusted closed and this would exhibit the same as above.

It could be a piece of busted metal/bearing between the gears.

It could be a seized or damaged bearing.

The above two faults would allow the engine to idle but on revving, the machine will bog down and not pick up.

In short, strip the blades off and check they freely reciprocate and then check the gearbox out. Gearbox parts can be very expensive so check them and make sure you find the part that has failed.

[Derekl]

Hi, thanks for the early response. Firstly it is not a pole trimmer, when the machine is cold everything works perfectly, engine revs, blades move and cut without a problem. If I keep the throttle open it will carry on working till I stop. However when I go to start again either with the engine ticking over or restarting the engine refuses to rev and the blades will not move. I did wonder if the plug was breaking down when hot, however I have replaced the plug and the problem persists. Again, any advice very much appreciated.

[spudulike]

Mmmm, that's a strange one.....my thoughts are that something in the gearbox or blades is heating up and binding or the engine is past it and not making enough power to reciprocate the blades.

Have you kept the gearbox filled with grease on ALL the greasing points?

After using the machine, does any part of the trimmer blade or gearbox feel very hot to the touch? 

When starting from hot, does the machine start easily and does it feel "punchy" when pulling over?

It is probably either the blades seizing (common after a lot of conifer resin build up) or the gearbox has lack of grease and a bearing is getting hot.

How did you test the blades are free and when cold, does the machine cut with normal power? We may still have a simple carb issue.

When hot, is the machine totally locked up with no blade reciprocation? Can you move the blades at all either by blipping the throttle or manually....with the machine OFF!!!

[Derekl]

Hi, I can’t say that I have checked the gearbox for grease, I did open it up and without stripping it down there was nothing obviously broken. When starting from hot the engine fires up first pull and feels fine. I really don’t think the blades are seizing as I have been able to move them manually after the problem has arisen and the engine is still hot. When cold the engine fire up second or third pull, blades start reciprocating when throttle is applied. Machine does cut with normal power from cold and will keep going until I stop, usually about 20min, it is after that the problem occurs. When everything is cold it all works again! Very peculiar. Again, appreciate any thoughts. I will be using the machine later today and I will see if there are any unusual hot spots.

Edited September 2, 2022 by Derekl

[Derekl]

Hi, just used the machine for 30min, worked perfectly, stopped to remove some trapped debris and the engine was fine but the blades would not move, they were free but there did not seem to be enough power to drive the blade! The base of the gearbox was very hot so I am wondering if there is an expansion issue of the clutch when it gets hot?

[Derekl]

Hi, just opened up the blade carriers and although there is grease in the housing there does not seem a lot. I will get some additional grease and see what happens. I am starting to think of a clutch issue. Do you think this might be the root cause.

[spudulike]

If the clutch was sticking shut, the engine would rev out but the blades won't reciprocate.

It sounds like something in the gearbox is expanding and getting tight when hot. The gearboxes do tend to get relatively warm with use. Does the blade feel hot anywhere along its length?

After 20-30 mins, do the blades still reciprocate from low revs and freely or is their signs that they are seizing up?

This may just be a case of stripping the unit down, clean, grease and reassemble.

[Derekl]

Hi, no undue hot spots on the blades after use. I think a strip down and clean and lubricate is probably the best thing. I will have a look at the clutch at the same time.

Cheers.