Hayter 56 Roller

[Fix'em all 49]

Hi all, I have unfortunately volunteered to replace the roller freewheels on my brother in law's Hayter Harrier 56 & finding it challenging to say the least. I have managed to remove one half of the roller but am I correct in assuming that the sprocket needs a puller to remove it from the shaft. The circlips have been removed from both sprockets but the large sprocket is  not moving. Any advice would be greatly appreciated. Cheers

Edited March 4, 2018 by Fix'em all

[Anglo Traction 1,016]

The large Sprocket in your first pic is/should be retained by what is known as a 'Selloc' Pin (Roll Pin). It really needs a correctly formed 'Punch' where the end has a smaller shouldered end that can pass into the Selloc pin's end and the outer larger surface to contact the end face of the Pin to prevent distortion of it. The Punch/Drift should be just under 3/16" diameter (5 mm is too big and 4mm is too small really)  

Once you have removed the Pin, it may require a 'Puller' on the Sprocket depending on the 'Fit'.

Once the Sprocket is off, the other half of the Roller will slide off the shaft leaving the various parts of the Freewheel ratchet/drive which is shown in your second image.

Plenty of lubrication on the Pin to ease removal.

Not an expert really, and maybe worth waiting for someone like 'Wristpin' to stop by and advise.  

[nigel 1,876]

Yep as Richard says 

[Phyliss 41]

The Hayter 56 (type 340 I think) had the circlip holding the sprocket on. If it doesn't shift with pry bars a little heat may be required but with the risk of damaging the bronze / plastic bush behind. 

 

In the past I have cut away the sprocket as close to the shaft as possible. Once the sprocket is off you should find a thin half moon key that transfers the drive. These can also be a pain to get out.

[Fix'em all 49]

Thanks for your comments, just been for a quick look & no sign of any roll pin. Will try to get a puller on it and a bit of heat. Is there any way to tension the chain or will it need to be replaced. It is far too loose & came off & jammed the drive up.

[Phyliss 41]

The chain jamming is the first issue that draws your attention to the rest of the drive. The mower goes forward but won't pull backwards.

 

Generally the bush behind the gear wears allowing the shaft to be baggy resulting in a slack chain. No tensioner is fitted so a new chain is required. Also check the cover hasn't worn. 

Edited March 4, 2018 by Phyliss

[Wristpin 400]

Its been a while but I remember it just being a woodruff key - no roll or spirol pin.  Had them so tight that the sprocket bends and enough heat melts the (relatively cheap) plastic bearing carrier behind it. Last resort is to cut the sprocket off. 

Thought that I had a service bulletin but cant lay hands on it at present.

This isn't the one that I wanted but may help. 55 is the woodruff key

[nigel 1,876]

Yes I was wrong 🙄 it’s my age

[Fix'em all 49]

I have got a bit further now but as mentioned I did end up cutting the sprocket off. I have ordered the freewheels but cannot work out how the old ones are removed from the shaft. Any advice gratefully received. Cheers, Ian

[Wristpin 400]

The freewheels are screwed to the welded boss on the shaft.

From here on I'm relying on memory!   Please accept that it's been six years since I retired and probably a few more than that since I was "hands-on".    

The freewheels are identical part numbers, not handed so they are fitted in opposite orientation so that the anti-clockwise rotation of the main shaft (viewed from the drive end tightens the assembly to the threaded boss that is part of the shaft and in turn engages the ratchets in that assembly to drive the LH roller. From that, it follows that the centre boss of the ratchet unscrews clockwise from the boss. If they are not too rusty and you look carefully at the ratchet units you will see that they have a little arrow inscribed on them indicating the direction of drive. If I remember correctly they themselves unscrew to come apart to reveal the ratchet pawls and springs. They have two recesses on one face to accept a pin wrench or to be carefully tapped round with a punch.

Viewed from the non-drive end of the centre shaft the RH ratchet will unscrew anti-clockwise - I think.

In the day, Hayter used to supply a complete shaft and ratchet assembly which was the cost-effective way of dealing with seized ratchets etc in a busy workshop.I can find the bulletin for the Harrier 48 but not the 56 but the idea is the same. 

https://www.dropbox.com/s/g345uah3qyls2og/Hayter Harrier 48 and 56 roller bulletins0001.pdf?dl=0

added later - the plastic cover, as per "Philliss's" post 

https://www.dropbox.com/s/y37o3y9zirvr2kl/Hayter Harrier 48 and 56 roller ratchet shroud0001.pdf?dl=0

Also, I believe that the nylon spacers were a "running modification" so may not have been present on earlier machines but can be added during repair.

 

[Phyliss 41]

As mentioned the freewheels have two indentations, that if struck with a suitable punch, should start unscrewing. Prior to this there should be a collar that is undone the same. Rotation wise if the shaft is clamped vertically in a vice ( on an area of the shaft that isn't used as a bearing surface) the collar will be uppermost. This & freewheels come off anticlockwise from looking down on the shaft end. In between the freewheels is a plastic cover and possibly two shims.

 

Assembly wise I don't think my method is right but I tighten them up with a suitable drift against a tooth of the sprocket. Writing on  the sprocket should face you as you wind them on. 

Hope this makes sense.

[Fix'em all 49]

Thanks for the advice guys. I had to get the grinder out again & cut the collar & both sprockets off. One thing I hadn't noticed was that  the raised tags on right hand roller had all  sheared off (I even posted a photo & still didn't see it). Not sure Hayter would do it this way but I cut  a triangular v out of all the wide tags and bent up  one of the 2 tags it created on each section. Well packed with grease & works a treat