Hedgetrimmer blades jamming?

[sandspider]

Hi all

 

I've got an aged Zenoah LRT2300 long reach hedge trimmer which has served me well. It's been stored properly, had the gearbox greased, blades lubed etc. but beyond that I've not needed to do much to it.

When I got it out of storage this year, the blades were jammed and wouldn't reciprocate. I assumed they were just a bit rusted up, gave them a good oil and a couple of taps with a large persuader and they freed up and worked fine. It cut as normal for about an hour,  then I put it away. When I got it out again today, the blades were jammed again. More oil and a jiggle and away they went again, but after another couple of batches of 30 mins or so of usage, the blades started to jam again. And now tapping doesn't seem to free them up.

Engine runs fine, blades aren't too tight as I can ease them apart a wee bit with a finger. Gearbox is greased. If I rev the cutter with the blades jammed the tip of the cutter bar twitches to the right slightly and the engine bogs down a bit but that's about it.

 

What's the next step to sort them out? I've never adjusted blade clearance etc. - perhaps I should! I haven't dismantled the gearbox or anything as I'm hoping it's a simple fix. Don't think it's a driveshaft issue as they cut fine when not jammed. Any ideas please? (I'm not super mechanically minded but I'm happy to have a go!)

 

Thanks.

[Gary Prentice]

The gearbox is straightforward, just a couple of circular cams. A parts diagram would be useful but if you undo the cover carefully (support the blade so it doesn't lever the workings out) it's obvious how it works. 

 

But before that, have you tried adjusting the bolts that hold the blade parts together? You might have a build up of stuff/rust between the component parts which is creating too much friction for the engine/gearbox. Try slackening the bolts and see if it resolves the problem. If it does you might have to disassemble the blade to clean everything properly but it isn't too difficult. Don't forget the spacers on the bolts when you reassemble.

[sandspider]

Thanks Gary.

 

Done that, tightened a loose bolt or two and tightened the nut which holds the trimmer head to the shaft. Blades now reciprocate again! Will give it another go later in the week and see if it jams again, but it's looking better anyway. ?

[Gary Prentice]

Sounds like a result!

 

And thank you for the thank you.

[spudulike]

Sometimes you get a bearing breaking down or a bit of debris in the gearbox that jams in the gears and cocks up the reciprocating of the head. You normally loosen up the blade clamping bolts and if that frees the unit up then the blades need taking off, cleaning of all that compacted resin and conifer shyte scraped off with a chisel.

The gearbox is pretty simple, just be thankful it probably doesn't have con rods like the HL135 heads where all the needles fall out when you remove them!!

[sandspider]

Cheers spud. If it happens again I'll dismantle and clean more...

[daveatdave]

I do not know about the Zenoah but some makes the bolts tightens the blade and the nut stops it from moving if it has been stored for a long while I would change the grease in the gearbox

I use a paint brush and old engine oil on my blades at the end of the day if I have been cutting sappy stuff a quick going over with a wire brush first 

[Stubby]

The bolts are usually " shoulder "  bolts ( like a built in spacer ) if the shoulders are worn down , even

slightly , when you do the nut up it will tend to clamp the blades .

Edited July 12, 2018 by Stubby

[lurkalot]

10 hours ago, Stubby said:

The bolts are usually " shoulder "  bolts ( like a built in spacer ) if the shoulders are worn down , even

slightly , when you do the nut up it will tend to clamp the blades .

Thought these were adjustable.  Like Maruyama / Echo etc.  Just screws washers and nuts, and a threaded support bar.