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Collection, Preservation and Display of Old Lawn Mowers

Atco Royale frustration.

Thoroughly enjoying being a new member of OLC and wish it had been around forty years ago to help with my battles with various mowers of yesteryear. 

I am having a frustrating time getting an Atco B24 performing as it should. Repaired a leaking float on the Tecumseh engine with almost forgotten soldering skills. Made new brackets for roller seat. Cylinder appears in very good shape and cuts paper all the way across.

Engine running well and roller pulls powerfully. Unfortunately  cutting cylinder not engaging.

Following the excellent advice on this forum I removed double sprocket and corresponding dog clutch which appeared damaged. Refashioned and filed into shape and hey presto all good.....for a couple of hours.

Having looked through forum several posts emphasing need for this to be set up properly which I thought I had.

The cylinder seems to have very little wear but I can move it laterally about 1/8 inch. Is it possible this lateral movement is causing the problem with the cylinder drive or is it all to do with the set up of the engagement of the clutch dog. 

I may have access to a used double sprocket and corresponding "cog" but don't want to fit it and wreck it if the cylinder bearings are the cause.

I will try and up load images separately.

Looking forward to coming to a rally when that becomes possible.

Thank you in anticipation



wristpin Tue, 06/07/2021

I think that any end float on the cylinder will make it impossible to set up the dog clutch correctly.

Lateral positioning of the cylinder is controlled at the drive end starting with the bearing at that end being against the step on the cylinder shaft with a distance washer and dirt excluding washer between the bearing and the step. The bearing is captive between its carrier and the chassis side plate. From there on the cylinder is located in position by the driving sleeve and then a fixing  - this part differs depending upon whether your machine is an earlier BSF one or a later UNF one. Either way, correctly assembled the cylinder should be clamped to the captive bearing with no end float at all.

I’ve known several attempts to recover damaged dog faces between the double sprocket and the sliding dog and none have ever succeeded due to the lack of precision needed to share the forces between all the teeth and the loss of hardening between the dog faces. You may be the exception, but...........   .


ManorParkMower Wed, 07/07/2021

Thank you Wristpin for your support.

I think I need to sort out the stability of the cutting cylinder before attempting to address the damaged sprocket and meshing dog.

I'm surprised at the lateral movement as the machine seems to have very little use, rubber on roller and paint work very good, no dents or dings in the chain cover. 

May end up just using it as a roller as it drives like a dream!


ManorParkMower Wed, 07/07/2021

Thank you Wristpin for your helpful comments.

I think I need to address the lateral movement of the cutting cylinder before attempting to sort out the double sprocket and dog.

The machine seems to have had little use. The roller rubbers very good nick, paintwork excellent, hardly any dings or dents in the chain covers or the frame, trailing seat still has original paint on roller. Really surprised that there is lateral movement, it looks in such good shape otherwise. I will strip it down and try and establish what is going on with the cylinder.

Once again thank you for your guidance, it's what makes the club such a pleasure to be a member of.


ManorParkMower Wed, 07/07/2021

Thank you Wristpin for your support and advice.

The machine seems to have had very little use, paintwork in excellent condition, no dings or dents in chain cover or frame, roller rubber very little wear so  I'm  surprised it has lateral movement. Bottom blade and cylinder very sharp.

I think I need to remove the cylinder and see if I can sort that out prior to attempting to sort the double sprocket and dog. 

Thank you for your very helpful comments, a pleasur to be a member of such a supportive club.


ManorParkMower Wed, 07/07/2021

Thank you Wristpin for your advice.

I think I need to address the lateral movement before I tackle the double sprocket and dog.

The mower appears in very good condition with minor paint scratches, roller rubbers very good, bottom blade and cylinder seem very sharp no dings or dents in frame so I'm surprised with this lateral movement.

The trailer roller still has original paint on the roller and in excellent nick which makes this issue so frustrating. It may end up being used only as a roller as it drives so well.

Thank you for your thoughtful advice, a benefit of being in such a well run club!


ManorParkMower Mon, 12/07/2021

Thank you for your advice Wristpin.

I removed the cutting cylinder and have stabilised the end bearing to stop lateral movement and float 

I have recontoured the dog and corresponding sprocket but accept it may not work.

Will keep you posted.

wristpin Tue, 13/07/2021

It would be interesting to know what was the cause / missing allowing the end float. On the subject of “ re-contouring” the teeth on the sprocket and sliding dog it is essential to maintain the undercut on the teeth that holds them into engagement  under torsion .

ManorParkMower Tue, 13/07/2021

The cause of the end float movement was that the clamp that holds the bearing on the right side of the cylinder was not tightened and the cylinder could move laterally. Now tightened there is no lateral movement. 

As you predicted my repair of the dog clutch and double sprocket has failed.

This may be heresy, and the very suggestion may involve suspension of membership of OLC, but could I fuse the sprocket and dog until I get a replacement?! I realise it means there is no disengagement and the cylinder and drive would not operate independently. 

Thank you for your interest Wristpin.

wristpin Wed, 14/07/2021

Needs must! I’ve never done it but I don’t see why you shouldn’t do it. The only thing that might give an issue is that the correct set up allows the momentum of the cylinder to over run when the main clutch is disengaged to avoid it feeding back up the drive train . Possibly closing the throttle to slow things down before disengaging the clutch will avoid any snatch back.

Possibly you can weld  the sliding dog to the sprocket or just replace the light engagement spring with a collar or spacer to hold the dog into position against the worn teeth trying to throw it out of drive. With correctly profiled teeth - undercut, it is the undercut that draws the two together not the force of the spring which only offers them up for the undercut ramps to lock them with a self servo  action.

ManorParkMower Wed, 14/07/2021

Thank you that all makes mechanical, technical and dynamic sense. All those methods of linking the drives together make sense but with inherent risk of the cylinder having momentum which will feed back up the drive train.

I'll give it a careful try and see what happens. 

Once again thank you for your very thoughtful advice, I'll keep you updated.