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Author Topic: Roller mowers and gearboxes.  (Read 2564 times)

Offline Mick

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Roller mowers and gearboxes.
« on: January 12, 2020, 02:45:54 PM »
Seems these days the gearboxes on most machines have gone to a what feels like a internal dog clutch, rather than a multi plate, or cone type clutch.

This is great and makes for a more positive drive, and of course doesn't slip and wear out as much.  Also means you're not having to constantly adjust it.

However, I worked on some roller machines recently, one of the Cobra roller mowers which they have fitted a massive and really heavy rear roller.  Gearboxes seem to fail on these quite frequently, so I can only assume it's the weight of the roller causing the failure. Having to bring this heavy (I mean really heavy) object up to speed in a blink of an eye can't be doing it any favors.   

Anyone else seen similar problems with the Cobra's



Offline Gregs mowing

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Re: Roller mowers and gearboxes.
« Reply #1 on: January 12, 2020, 04:36:19 PM »
Never heard about cobras drive before but suggests pretty shabby testing used when designing the mower. Think the 2 beefiest gearboxes out there are the hydro from the hrh 4 wheel and the weibang 3 speed. Both different designs. Hope hayter have better luck with gearboxes than in the past, my 41 pro has lasted 3 years so far...
« Last Edit: January 12, 2020, 06:02:17 PM by Gregs mowing »

Offline Mick

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Re: Roller mowers and gearboxes.
« Reply #2 on: January 12, 2020, 04:40:06 PM »
Hi Greg.  They're pretty shabby mowers to be fair.  Some better than others, but built to a price.   

Offline GardenKit

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Re: Roller mowers and gearboxes.
« Reply #3 on: January 12, 2020, 10:17:24 PM »
As has been said, there are some pretty shabby gearboxes around, on some pretty shabby mowers. But the development of these mowers have been driven by the appetite of the general public for the cheapest mowers they can buy.
Quality only comes at a price and there are many of the better brands out there with some pretty decent gearboxes to be fair (although Hayter have fitted some pretty poor ones since 2000.)
But to be fair to even the cheapest gearboxes the failures are mostly due to poor use. Many, operated correctly will give years of service.
There are several main causes for gearbox/clutch failure.
 1) The clutch cable has not been correctly adjusted "out of the box"
 2) The clutch cable has not been adjusted during use, as the clutch wears
 
 1) and 2) will give rise to a slipping clutch all the time the mower is being used, and of course if 1) is the major culprit then the need to adjust the cable soon in life will be necessary.

If the cable is not adjusted the clutch just keeps slipping until is self destructs.

 3) another reason for clutch wear is that some users will insist on deliberately slipping the clutch in order to slow down the forward speed. This will destroy a clutch/gearbox very quickly. The clutch lever should always be fully engaged, or fully disengaged, never part way in between.

 4) All gearbox and clutch life can be extended by keeping the cable adjusted ,and also by taking the startup torque loading off. In other words an operator should not pull the clutch in and let the mower pull off from a standing start. Instead, if he takes a step forward and gives the mower a slight push to get it rolling before pulling in the clutch lever the gearbox and clutch will last for many years.

Offline Mick

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Re: Roller mowers and gearboxes.
« Reply #4 on: January 12, 2020, 11:51:54 PM »
Barrie,  I absolutely agree will all you just said.  I'm wondering if this is why some (not all) of the modern gearboxes seem to engage more like a dog type clutch, they're either in or out, nothing in between any more.

1) and 2) Agreed again.  In addition, people who crush and bend the cables when folding / unfolding handles really doesn't help, and continued use with the clutch cable in that state is only going to go one way.  They could save themselves a lot grief and money just by looking after the cable.

3) Already seen this happening on the new Hayter Harrier pro's because they're much to fast.

4)  Especially recommended for Honda HRD 536 QX and HRH 536 QX machines.  Just wish the operators would listen. Those boxes are expensive to repair.  Another thing that bugs me about these is the clutch cables, they use a coated inner, and they roughen up and go stiff after a while.  No way do you want the clutch engaging slowly on one of these machines, or it'll soon be jumping on the drive.
« Last Edit: January 13, 2020, 07:53:43 AM by Mick »