Atco rear roller
I have recently aquired two Atco's 20" with Villiers 4 stroke engines, belived to be from around the1950s. On one of the mowers when drawn backwards the rear roller will not turn but WILL turn in the forward motion. Is this a common problem? Can it be simply fixed, and how? Otherwise the mower is in great condition.
Really need some more specific model info' but this is probably the set up assuming that your machines have two piece rear rollers.
The rear roller shaft is driven by the chain and sprocket and transfers the drive to the two roller sections by two spring loaded face ratchets that slide on a hexagon driver which is fixed to the shaft within the rear roller assembly. The spring forces the ratchets outward so that they engage indentations within the two rollers.
Under normal conditions the two ratchets engage both rollers transmitting equal torque to both. During tight turns or pulling back one or both of the ratchets disengage allowing free movement of one or both rollers.
Your problem is probably caused by rust etc on the hex driver preventing free movement of the ratchets. You may be able to ease them by a good squirt of light oil between the roller halves but to do it properly you will need to get into the roller. You can either drop the roller out or remove the non-drive side chassis member and just pull off that roller section, clean up the hex driver and reassemble. I would just lubricate the hex driver and ratchets with a little light oil or the sort of white grease aerosol spray used for car door locks etc. Avoid heavy grease which will attract dust and dry out and bind the ratchets.
If your machine has a single piece roller there will probably one spring loaded ratchet at the drive sprocket end but here again it is possibly binding and preventing pull back.
In addition to the very comprehensive advice given by wristpin you could also disconnect the drive chain to the rear roller sprocket and then try moving the mower, if it now moves freely in both directions the problem could lie elsewhere on the machine, for instance a dragging clutch.
I agree with hillsider, the problem probably lies in the drive system and not the rear roller. As you can push the machine forward it is unlikely to be the roller, as the rachets seem to be working. When you pull the machine backwards, the rachets drop into place and try to turn the shaft in reverse, if anything is binding it will not turn, which is the problem that you have got.
The problem could be something as simple as one of the chains being too tight, try slacking them off, this is usually done by untightening the nut that holds the shaft that the 'idler' sprocket rotates on and sliding the shaft about until you get the required tension in the chain. This tension is probably a lot slacker than you would imagine, once you get the right tension, retighten the retaining nut.
The clutch could also be dragging, so if the chains are ok, have a look at this, but this would also give you the problem that the machine wouldn't stand still with the clutch seemingly disengaged.
As Wristpin said, it might help if it was known just what model of 20" atco you have.
Thank you all for replys and sound advice. I removed the rear roller and inspected the ratchet mechanisms. These were free from rust but had large amounts of solidified grease and accumulated debris, they appeared to be working ok. I then looked at the drive chain which was tight as the drive shaft appears to be bent (now removed for straightening). Taking off the chain all worked perfect and the resistance was no longer there. There was also slight binding from the clutch. So all should work fine when put back together.
I am unable to find the model for the mowers I have though they are very common. They look like a typical Atco middleweight, 20" cut though I have another with a 24" cut also a similar mower. All have Villiers 4 stroke engines. Is there anywhere in this website I can find images of lawnmowers with the model names next to them? I am new to this mower obsession and have no Idea what the machine looks like when I read the name. For example when reading the for sale ads in grassbox.
Wristpin, that is a very good parts explosion diagram. What document is it from?
I have acquired a number of Atcos (a 12 inch and three 14 inch) which I want to restore. I have searched the Internet high and low for workshop/service manuals to no avail. I have purchased a couple of small Atco parts manual booklets, but they don't give anywhere as much detail as the diagram you linked to.
The material that I posted was scanned from manuals that I acquired back in the late 70s. If you can be a little bit more specific about what you have I will see what I have that may be relevant..
I have a 1249 and another, incomplete, 12 inch of unknown year. I have a 1457 two stroke, a 14 inch 4 stroke (I guess 1960s) and another 14 inch of unknown year that is incomplete.
I also have some spare Midget Mk1 engines in varying states of repair.
It is my intention to end up with a fully-restored 12 inch and a fully restored 14 inch two stroke. (I haven't decided what to do with the 4 stroke as yet.) This will involve complete disassembly, cleaning, repair, repainting and reassembly.
As with any mechanical work I undertake, I like to have the applicable workshop manual on hand, especially if it has parts explosion diagrams which I find are a great help.
From my fruitless searching of the Internet, I would say that those manuals that you acquired back in the late 70s are very rare.
PS: I've sent you a private message.
The majority of the manuals that I have are parts lists, not workshop manuals and are for 4-stroke machines but they do have nice clear "exploded" illustrations so I will scan one and post a link.
No private message received!
Many thanks. That is very useful indeed. Very kind of you.
Seems the private messaging system may not be working, though I did get a copy of my message emailed to me. Is the email address in your profile up to date?
I've checked the email address and it's correct. Have also sent you a test pm.
Received that PM, thanks.