OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Question On Scott Bonnar Cylinder Mowers Drive clutch on mod 45

Hi,
got an old model 45 with a 2 Hp series 6 B & S in it,
The drive clutch does not seem to disengage properly making it very hard to push .
Pulled it down but I can not see any type of return mechanism .
I was expecting a small spring between the pressure plate & the cork plate but there is nothing in there.
Is that correct ?
Or has some thing turned into dust one the past 40 years ?

Hello Rovert,

Welcome to the ODK forums. I'm sure we can help here.
Could you confirm you are talking about the land-roll clutch that propels the machine forward?

If so, this is Scott Bonnar's 'hair-trigger' clutch. It is extremely durable and reliable.
There is no need for a return spring in the clutch plate design because this clutch works in
reverse - you don't let the clutch out; you let it in by squeezing the trigger.

It may be that the plates were 'sticking' because of accumulated grease build-up.
The nut (85) and bolt (84) should be adjusted so that you have free travel of the machine,
(minimal clearance between the plates).

Photos would be most helpful here. How is the cork clutch plate lining?

Here is a exploded view:

Yep,
That is the animal.
The cork is a little polished so I might give it a quick once over with the zinc sterate ( 320 dry ) paper ).
The cork is quite thick so there is plenty of drive left in it.
The centre of the drive plate (no 68 ) looks like there was once a compression spring around the central boss as it is quite rough and I am definately not the first person to go in there .
Never pulled one down before so I was a bit bemused that there is nothing to separate the plates when the cable is released.
Thanks for the diagram.

Hi Rovert,

I can confirm what CyberJack has said and that is there is absolutely no spring in there and it is a very simple design, ever so slightly lose for no drive, thus no friction between the plates and when the land roll clutch lever is squeeze the clamping effect brings the cork plate and clutch plate together to provide the drive. There really isn't any need to roughen up the cork as it will just smooth off on the first application. Clutch adjustment is what it's all about.

Cheers,
BB

Thanks,
I play a lot with old motorcycles so am familiar with cork as a friction material.
There is some grease smears on the cork which I will sand off.
Also a bit of grease on the bolt & two sleeves which looks to be a bit thick.
It dfinatly dragged badly when I tried to push it forwards.
backwards was fine but that of course is the drum not the clutch.

Don't think it's a great idea to use dry-lube paper for this job. Better to use ordinary wet & dry paper, wetted with water if you want to use it wet.

A bit late so sorry for the rudeness ,
Thank you for your help.
It went back together well and everyone is happy.
I use the Zinc paper because I got 5000 sheets of it at a clearing sale for $ 20
Gave a mate who is a plasterer 1000 but he uses power tools mainly and buys pre cut abrasives to suit his gear.

So Rovert do you know anything about Royal Enfield clutches?