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Author Topic: Variable drive systems  (Read 266 times)

Offline Mick

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Variable drive systems
« on: June 22, 2018, 06:01:49 PM »
So over the last few weeks I've noticed a shift in using a certain variable speed system, the one with a spring loaded split pulley on the engine crankshaft, and a variable split pulley on the gearbox adjusted via a cable.  I know Viking mowers have been using this for some time now.   Seems to be a pretty flimsy method of controlling the speed, and already I'm seeing problems with cables belts etc. 

It has other obvious flaws in its design, such as if the cable breaks it goes to full speed and stays there.  As the belt gets worn the machine gradually speeds up,  until eventually the belt gets so loose it stops driving.

So far the machines I've noticed using this very same system (or method) appear to be,

Viking / Stihl MB-VR and MB-V MB-VM
The new Hayter Harrier 41 375 and 376 series.
Cobra's new Variable drive roller mower.

Have to say in all the years I've been repairing this stuff, I'm not impressed by this at all.  ::)

So just out of interest, what other mowers have you seen using this system?



Offline Mick

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Re: Variable drive systems
« Reply #1 on: June 23, 2018, 11:31:04 AM »
Attached to the post above, a little sketch I made of the basic system these manufacturers are using.  It's not to scale or anything, but just outlines the basic principle, and how it works.