OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Question On Scott Bonnar Cylinder Mowers s/b 45 front shaft

hi all! The front roller shaft ends and shaft become worn over time and become slopy this can affect the cutting hight. it is very aparent as the roller shaft will have wear marks i bought a new shaft but the roller ends needed sleeving i found some brass tube at a hobby shop that fitted nice over the shaft but a little loose inside the roller ends so i cut some very thin brass sheet and fitted that into the roller ends then the brass tube over that seems reel good now feedback kindly appreciated steve....

The first issue is in controlling which joint slides and which joint locks. The conventional approach would be to press the bushes into the roller ends, so the brass only slides on the steel shaft. However it might be tricky to get the shims tight enough in the roller ends, because it is difficult to press the bushes in with the shims wrapped around them - usually the shim slips as much on the bush as it does on the plastic roller, so you end up with the shim protruding at the end, and if you cut that off, only half the length of the bush is a tight fit in the roller ends. All that is a bit esoteric - it looks in the picture as if you've got the shim all the way in, somehow.

The other concern I have is metallurgical: what material are the roller ends made from? In the picture they look like aluminium. Aluminium and brass are incompatible: they set up a million little voltaic cells, and the aluminium part is the sacrificial anode, so the roller ends get eaten up fairly quickly.

All of this is resolvable, at least in part. If the roller ends are actually plastic rather than aluminium, the second issue doesn't arise. If they are aluminium, you should use aluminium bushes.

Hi Steve and grumpy, the alloy roller end caps were standard on the SB Model 33, 40 and early 45's... the company then changed to plastic, which are on my 45. It is a very domestic set-up for such an expensive machine (when new)...(ie.)a mild steel shaft with a plastic end caps connected by a hollow round tube, with no lubrication in a hostile environment...dirt, dust moisture...it is no wonder that the shaft wears so quickly...at least Steve's model alloy end caps have a small hole (you can see it in his pic)that was for the oil-can to lube the area....but the industrial mowers such as the Model 17, have a solid steel roller with greaseable roller bearings, I think you will agree a much better set-up.
Steve, IMO, it would be very difficult for you with the shim and bush inserted to line up the oil hole for shaft lubrication.

Deejay, with bushes you usually just drill the oil hole through the bush after you press in the bush but before you put the axle through, so it always lines up.

The plastic end caps could work reasonably well if they were cheap. It is like the unlubricated plastic wheels on a rotary mower: they do wear out, but you just replace them and soldier on. However it is different with a metal-on-metal bearing that is dirt-lubricated: it wears quite quickly, possibly seizes up, and is relatively expensive to replace.

If you don't use replaceable plastic bearings, the next step up is ball or roller bearings, grease points, and proper seals to keep dirt out. In cost terms, that is a very big step.

Yeah sad fact to replace the Plastic ends from time to time, but that's about it hey.
I personally detest the feeling of the plastic on metal and do lubricate these every else and a while, but now that I have bought myself a lathe, I will look into making a few ends caps to take sealed bearing and set them into them.
I have a few neighbours that are also keen to replace these with bearing types. When I get the chance, I'll post my units.

Mersenne, the sealed bearings may not survive all that well if they are exposed to water. The inner and outer races of each bearing will rust at their ends, and then the rusty races will tear up the plastic side-seals of the bearings. I think it is more usual to use a grease compartment that is lubricated from time to time with a grease-gun, via a grease nipple. If you have a close fit or a labyrinth seal on the end-plate where it runs on the axle, it will probably only need a couple of strokes of the grease gun each couple of years. That will re-fill the grease compartment and push a tiny amount of grease through the labyrinth seal. Any dirt present will be pushed out with that grease.

Grumpy, my SB's and the ones I've worked on have all been plastic cap front rollers, unlike the above pics by Deviosi and even with no wear in the front roller bar the plastic caps have too much 'play' in them, hence my wanting to machine up new caps and fit bearing to them. The intention is to have the bearinng inside the caps.
I hear you on ingress, but hoping the design would be efficent enough to overcome this.
I'm keen still to so anyone's pictures of their of a grease nipple setup though please.