OutdoorKing Repair Forum Forums Repairs and Maintenance Questions On Ride On Mowers Questions on Rover Ride On Mower Rover Rancher Autoddrive - Chain Adjustment

Hi all, nice to join your community.
I have a rover rancher 17HP.
The primary drive chain adjuster is slipping, despite me tightening as much as I dare.
Access is tight, with the drive discs (?) close. Thus not possible to get anything but an open ended spanner or a ring spanner with virtually no offset. Size of bolt head also problematic, with my 11/16th too small (perhaps the head was a little damaged prior to me attempting to tighten, but not significantly). The best I can manage is a 3/8th whitworth.

Are there any tricks to this process?
Thanks in advance for your consideration.
Happy to attach photo if needed

Hi Wilbur, welcome to Outdoorking. I think a picture is essential, so that we can all understand what is happening. Prior to seeing that, it sounds as if your chain is slipping due to worn-out sprockets or excessive slack. Normally chain adjusters are not required to be tight, and not capable of it - they just ensure there is not so much slack that the chain falls off.

Thanks for your response.
The problem is that the tensioning mechanism is slipping, thus the chain that has, say, 10-15mm movement max upon adjustment will, within an hour of hard use, have 30-60mm movement or more, ending up coming off the sprocket.
This model has 2 chains (see photo). The procedure for correctly tensioning them specifies to firstly tension the primary drive chain (on the left in photo). This chain only connects 2 sprockets (there is no third sprocket like in the secondary chain), with the tensioning achieved by moving the driving sprocket (the front sprocket) backwards or forwards in a slot in the mounting plate. The bolt head (just visible in photo) is difficult to access as indicated in the first post, meaning that I can't get a ring spanner on it, and I don't want to round the head with an open ender applying a lot of force. It is this tensionig mechanism that is slipping, with the tension applied by the bolt not enough to stop the sprocket moving towards the other sprocket, thus loosening the chain.
When this mechanism slips, the secondary chain also is loosened.
If I had excellent access, I would remove the bolt, clean the mounting plate that the bolt holds the sprocket axle to, and generally investigate. Unfortunately, this can't be done without a lot of fuss.
I suppose, ideally, there might be someone out there who has experienced the same or similar problem..............
How do I know what amount of movement is recommended for such chain set ups?
Thanks for wading through this...............

The chain mustn't flop about, or it will fall off when it thrashes about under load.

I can't find the adjusting bolt you mentioned in the picture. Such things are usually designed to be accessed with a socket spanner, often with an extension shaft so that the torque is applied far away in a spacious region. I can see one smallish bolt running laterally on the right side of the picture, and it looks to me as if it can be accessed with a socket and perhaps a short extension.

Mechanics are not fond of barked knuckles, and engineers are usually trying to design things that mechanics will cope with successfully. Any time the job involves lousy access and skinned knuckles, it's time to replace the design engineer. Can you post a picture that shows the bolt and its environment?

I have an 18 hp Rancher and have had the same drive chain adjustment problem. I use a 18mm open ended Sidchrome (quality.) i suggest as I hve done loosen the adjusting bolt head out a few mm and clean with an aeorsol cleaner. get some course valve lapping past and feed it in between the clamped areas as much as possible. Re tighten the chains as per usual and keep mineral oils away as much as possible. use a silicone lube on your chains. i have a rancher was 18hp now for 7 yrs and with the friction drive and solid rear axle doing 10km/hr its hard to beat these machines for value for money. pity Rover has taken them off production. (It is still possible to get parts though) I have now fitted a 25hp TWM V twin and also replaced belt tension springs with heavier ones to handle the extra grunt. I can say with 2000hrs experience that the the Rover Rancher is a great machine.