Skip to main content
Collection, Preservation and Display of Old Lawn Mowers

Atco B20 Deluxe

Been servicing the above mower, it has been stood around for about 8 years or so, it runs fine now and all the chains move as they should..

The problem I have is the roller will not roll on its own,  the cylinder turns as well, even though the cutter release lever is lifted and pulled clear of the notch.

Greatful of some advice, maybe something needs adjustment..

The only other thing I have noticed is when the mower is manual pulled backwards, there is a clicking from the spring in front of the carrier/ dog clutch which engages the sprocket wheel on the cylinder, is this normal or not


many thanks


wristpin Wed, 01/12/2021

Just to make sure that we are talking about the same machine, please post an image of the chain side with the cover removed.

wristpin Wed, 01/12/2021

Try slackening the chains a mite. Remember that the primary chain sprocket is both adjustable in its slot and also its eccentric . Also that the intermediate sprocket is adjustable by releasing the big nut up inside the chassis . I’ve got a bent open ended spanner to make the job easier. Also. Make sure that when the cylinder disengagement lever is locked out the disengagement fingers on the rocking lever are holding the moving dog clear of its mating teeth on the cylinder sprocket. Equally important, when the dog is engaged those fingers are clear of the dog  - ensuring full engagement..

I’m a bit puzzled by the freewheel dog on the end of the roller shaft . Doesn’t seem to have any function.

wristpin Wed, 01/12/2021

Think that I’ve answered my own question re the dog on the roller shaft. What you have is a “ Club”. There will be one on the other end for engaging with the transport wheels for a golf greenskeeper to motor it from green to green. Guess work ?

Flowerpots Tue, 07/12/2021


Found the problem...or should I say culprit 

someone had put a small nut on the top bolt holding the release arm instead of a washer, thus the spring couldn't be either compressed or released properly causing the dog clutch to not release.

wristpin Tue, 07/12/2021

The culprit seems to have escaped - no image, but we would sometimes find that a previous repairer had incorrectly reassembled the rocking arm,84,  that disengages the cylinder clutch dog. In particular we would find that the spacer, 77, was the wrong side of the spring,85. With the lower of the two 83 nuts done up tight against the shoulder on stud 86 , the rocking lever should be free to pivot against the spring and spacer enough to move the clutch dog through its travel. The upper nut 83 providing the required adjustment.

Flowerpots Tue, 07/12/2021


Flowerpots Tue, 07/12/2021

Thanks for image

it was the upper spring 100 on your diagram which had the nut attached instead of the 3 washers. Works beautiful now with the washers....

cheers ..