I am restoring a 33 - I have the original clutch but the assembly has me perplexed. I sourced a 45 clutch lining (thinking that they would be the same?) but the thickness of the lining does not allow the cone to bed down. The cone is only about a third into the corresponding section before it binds and the back section will not come together because of the incorrect fit. Any advice?
Yes the later 33's had the Model 45 clutch fitted as they were built side by side with the 33 being sold as the Lawnking until it was dropped and the Lawnking was a 45 as well.
I live a 24 Hour lifestyle, but every now and again I seem to fall asleep, well at least that's what my wife tells me.
The 330413 doesn't actually show an engine clutch lining. The 330026 shows a 45 style cotter pin clutch with lining (guess this is the same as a 33001 lawn king?).
There doesn't seem to be any literature on a Bonmow/ Villiers type 33, but I've got an early flat handle bar/ wooden roller 33 so I'm curious.
(a) 33 919 - flat bar handles (which I am restoring)
(b) 33 10569 - chrome round section handles which can be halved in length for transportation.
I have (2) two inner cones - which are the same and one outer cone with it`s rear mating surface. So the clutch is a mix mash of parts. Unlike the 45 clutch there is no grub screw to the shaft - mine has the collar and lock nut.
I have a Scott Bonner Operating and Maintenance Instructions booklet Model 33 16inch 330026.
I have (2) two engines - Villers Midget 98cc 1953 * and a Kirby Tecumseh.
* this engine came off a Model 19 Scott Bonner which was very rusty - I have some parts that I saved from this mower.
So the early 33 clutches did not have a cork lining like the 45`s - Just metal to metal cone surfaces?
Thank you for the diagram showing the 33041 model.
My 33 919 plated solid deck is different to the one shown in the 33041 diagram (my 33 10568 mower) in that the engine clutch fork mechanism does not sit on a raised block # 138, nor does it have the "bracing bracket" # 150. The engine bolt holes (4 of) in the solid decks are drilled in a different position to reflect the different engines used and the clutch mechanism holes (3 of) are drilled in a different position (to allow the use of the bracing bar on the 33041?)
So the early 33 clutches did not have a cork lining like the 45`s - Just metal to metal cone surfaces?
It makes no engineering sense - to me - that this cone clutch worked without some clutch lining
Yes as we know the cone clutch is one of the cheapest clutches to produce so why not make it cheaper again and have metal to metal contact.
The Qualcast Royal Blade from memory has no lining on the cone clutch just metal to metal contact ,I've looked at a Qualcast Royal Blade cone clutch before but haven't seen the SB 33 apart from this Forum.
I can think of a few examples where this type of cone clutch does not have a replaceable clutch lining eg.synchro rings used for automotive gearboxes ,LSD differentials used in many vehicles but these two examples are in a wet environment.
The cone LS Differentials are metal to metal contact.
The old push bikes that you pedaled backwards to operate the rear brake had a type of cone clutch and from what I remember there was no clutch lining on the cones just metal to metal contact and bikes were in hostile environments.
Outboard motors use a cone clutch without a clutch lining.
I will see if I can get some images of the Royal Blade cone clutch.
Thank you for expanding our understanding of the operation of a metal to metal clutch. Neither surfaces of the inner and outer cones of my SB 33 clutch exhibit any signs of scoring / wear. I will have to wait till I have the mower assembled (awaiting a part for the rear roller) before I put it to the test.
No problem Malcolm and Jack ,another item I saw that you probably wouldn't think of having a cone clutch was a 1880 stop watch, I've finally got some images of the Royal Blade cone clutch .
This relates to the discussion of the Type 33 SB. I have one like this with the dry cone (cast iron) clutch and it works ok and is quite common for light duties (low power transmission).
Can I take this opportunity to ask a few questions (I am new to this Forum) ? Directed to Jack mainly. 1.- When you refer to "Model 330026" the "0026" is not the number on the name plate, Is it? (My mover has a "33 2887" number on the plate. 2.- My mower has tubular, one piece handlebars (like 330026 exploded drawing) but has a Belt Drive (like 330413) and a grommet on the chain cover. 3.- Any chance of getting a better resolution pdfs of the exploded views and spare parts listing.
G'day Max, Voytek S and all cone clutch lovers I wished I had never said that that clutch lacked engineering sense. I should have said it made no sense in Scott Bonnar history.
I have since learned that Scott Bonnar did use a friction cone clutch for reel protection on their post WWII Model 19.
The obvious question is why did SB abandon the 33 clutch when it introduced the Model 45?
Maybe the answers goes to the properties of cast iron versus aluminium. Any ideas?
I was thinking it would depend on engine choice used on a particular reel mower as to what cone clutch is used for instance if the engine choice was a Tecumseh horizontal shaft with an alloy flywheel you would need a cast iron cone clutch to act as a rotating mass (flywheel) but if the Briggs and Stratton horizontal shaft motor with the cast iron flywheel is used then the alloy clutch was fitted.
Heavy Flywheel = Light Clutch and Light Flywheel = Heavy Clutch
That's what i was thinking from a design perspective .
Jack Do you have access to SB production data? I would love to know what year my mower was made. (2887). I am restoring my beloved one, less new engine (I'm putting in some bloody Chinese thing, but matching the Briggs and Stratton 2.5 HP original one). Will post some pics soon, when she is up and doing her job. Cheers
Do you have access to SB production data? I would love to know what year my mower was made. (2887).
Hello Voytek S Alas, no records survive from the later SB period.
Quote
Heavy Flywheel = Light Clutch and Light Flywheel = Heavy Clutch
Hi Max, the thing is that the light-flywheel Kirby powered both the 33 and 45. The same power unit was coupled to both clutch designs.
I can only make this point: - The 45 was the first SB scalable reel design - meaning that it could be made in 14, 17, and 20" variants - all with the padded alloy cone clutch. The 33 was a one-size design.
For me, the padded clutch, using die castings, simply saved SB money - at a time when reel mowers were being challenged by the rotary revolution.
As we know mower engines need a certain amount of rotatable mass to stop the motor kicking back on start up and low rpm .
The alloy cone clutch with the light alloy flywheel doesn't seem like it would be enough to overcome the kick back problem.to me unless the alloy cone clutch is a lot heavier than it looks ( eg has a metal weight cast inside it)
I've never owned or worked on a Scott Bonnar reel mower so I can only comment on what I see from the images but I don't think the alloy cone clutch has a heavy weight cast inside.
Mower manufacturers don't always use a cast iron flywheel to increase the rotatable mass when using a light rotatable mass on the pto side of the crank (eg alloy cone clutch / alloy pulley ,light bar blade with light boss)
I quickly had a look at 3 Flywheels 2 Wipac and 1 Phelon ,I have limited knowledge on Scott Bonnar reel mowers but have seen a few removed Kirby motors ,I saw Scott Bonnar motors using Phelon Flywheels but have no idea what type of cone clutch was originally attached to these motors .
Looking at the 3 flywheels I have ,the light Phelon flywheel weighs 620 grams ,the light Wipac is 650 grams and the heavy Wipac is 1,360 grams ,so I would think the light alloy cone clutch would use a heavier Wipac or heavier Phelon flywheel compared to the Kirby motor with the heavy cast iron cone clutch.
The heavier alloy flywheel weighs more than 1 litre of water and a little more than double the weight of the light alloy flywheel.
That's what I was thinking looking at the parts but can't confirm without more info or having the two different Scott Bonnar cone clutch mowers in front of me.
Max, The mass of the things attached to the shaft is only a part of the equation - the distribution (or otherwise diameter) of it/them is another important part. It is called "moment". Light weight but large diameter disk will produce larger moment of inertia then heavier but smaller diameter one. I am sure you agree with me. Cheers Voytek
Yes well done Voytek the Scott Bonnar 33 looks a very successful restoration , you'd be happy the 33 turned out this well.
I know if two cylinders have the same mass but different diameters, the one with a bigger diameter will have a bigger moment of inertia, because its mass is more spread out. Similarly, if two cylinders have the same mass and diameter, but one is hollow (so all its mass is concentrated around the outer edge), the hollow one will have a bigger moment of inertia.
A rotating object also has kinetic energy ,It follows that the rotational kinetic energy given to the flywheel is equal to the work done by the torque.
The more mass an object has, the more kinetic energy it has.
If I have an empty drink can and compare it too a heavier smaller solid off cut of metal rod the off cut will have more kinetic energy than the empty drink can.
I know what you were referring to Voytek with the " Light weight but large diameter disk " but I just thought I would explain how the mass of an object can still be a critical factor.
My SB33 is back in one piece after the rebuild, the cone clutch without any friction material works well - I just needed to adjust the "adjuster" lock bolt to stop the clutch disengaging and away we go.
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