OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Question On Scott Bonnar Cylinder Mowers Adjustment of rear drum

Hi all,

Over time my 17" SB 45 (has started to cut deeper on the left hand side (chain side). I think part of the problem is that the plastic ends on the front roller have a bit of play, but it looks like rear drum is not parallel with the bed knife and requires adjustment.

Leaning the machine forward on the front roller, I'm using a straight edge from the front roller past the bed knife to the rear drum roller, but it's as if I need 3 sets of hands. Is there an easier way?? Should I have the mower on a flat surface. I'd really appreciate a step by step walk through of the process and any 'tips, tricks or home made tools' that people have come up with to make this operation easier. As a SB tragic with 6 45's, 2 Supercuts and an Old style queen, I'd happily put some time into making a jig or similar to make the adjustment easier.

Thanks

It may well be worth replacing the plastic ends of the front roller if they do have play as if you just adjust it, once they move aain you are back to square one.

You're right Joe,

I'll be replacing the plastic ends and probably the steel shaft as well which has grooves where plastic (and dirt) wears againsts the shaft.

I recall Bruce describing a simple alignment device used in the trade to check SBs. I was advocating the use of a flat piece of concrete when he explained the tool and the way it is used. You should be able to find it in the archives - I think it was less than a year ago.

Hi grumpy and TJ1, I think grumpy you might be referring to one of my posts regarding the aligning tool used for Scott Bonnar cylinder mowers (though for the life of me I can't find it! )
Here is a pic of the tool:



The tool is made from square section rod with a threaded hole complete with a dome headed screw and nut that is located closer to one end of the rod than the other. I purchased this tool from Turf Machinery Services many years ago.
The idea is to lay the machine back on its handles (careful here as the engine oil will displace throughout the engine and can cause problems....best to do this while doing an oil change, so the sump is dry)
You place the rod so that it contacts the rear roller and the front roller with the lip (edge) of the dome headed screw contacting the top edge of the bottom knife blade.
Then you slide the rod from on side of the machine to the other, checking as you go that the lip of the screw is in contact with the bottom knife blade....if it is then the cut will be level and perfect.
I would replace the front roller shaft if badly worn on both areas where contact is made by the end caps, and the plastic roller ends if possible before you do the check, this will assure that there is no play in this area and negate your efforts.
Best of luck with it,

Thanks Deejay, I seem to recollect Bruce participating in the same thread, and showing or describing a similar tool, but what you have just posted seems to cover the ground very well.

Thanks Grumpy, no probs mate,

Thanks Deejay - I'll knock something like that up and give it a try. May even tap a number of holes in it to accommodate various SB models.

Hi TJ1, this particular tool suits all SB models from the Queen bowling green mower to the 14" Model 40 SB terrace mower. Here are the dimensions:
Total Length: 1ft 6 1/2"... (47 cm)
Length from end to centre of tapped hole: 8 1/2"... (21.5cm)
Square section rod: 1/2".....(12.5mm)
Drill and tap and use a suitable 5mm dome headed screw and nut.