Is anyone familiar with the Hayter Harrier petrol lawnmower auto-drive system ?

[mikej2005]

I realise that this is a bit of a long shot but has anyone ever changed the drive-belt on a Hayter Harrier 41 petrol lawnmower (or other similar Hayter model) or is anyone familiar with how their auto-drive systems work ? The ones in question are the ones driven by a pulley attached to the side of the engine (so not the models driven by belts within the mower, above the blade).

My Harrier 41 is the 306R which is a 20+ year-old model which has a V-belt, driven via a pulley on the side of the (Briggs & Stratton) petrol engine - the pulley comes in two halves (separated by washers) and is fixed to the pulley drive-shaft via a bolt.

Basically, the two pulley halves on my machine are loose and I could do with knowing whether this is normal before I attempt to reinstate the belt (the mower doesn't currently have one fitted as I cut it off a good few years ago). As far as I know, the belt I removed was original (so the auto-drive system has never been interfered with), plus the bolt that holds the pulley halves and washers in place is as tight as it will go.

Here's a short video to show how loose the pulley halves are :

I guess it's possible that the V-shaped belt will push down into the cavity between the two halves of the pulley when the auto-drive is activated, pushing them apart and making everything tight, but I'm not familiar with this type of system so don't know if the looseness is intentional or not.

If anyone familiar with this type of set-up can give me the benefit of their experience, I'd really appreciate it. Cheers !

 

[Burnerman]

Can you shift the central bolt and let us see the state of those washers please?
Some systems used washers to tension the belt, others had a belt that rode up the pulley to increase the mowing speed.
For sure, make sure the belt you have is the correct one.....it’s section will give us a clue.
John

 

[Old Salt]

The halves of the pulley are meant to be loose but I dont think they are that loose. If you type intoyou tube “micks mowers hayter drive” you will pull up loads of videos that show different drive issues and how to fix them. Mick also does a live stream on a Saturday night at 6.30 where people ask for advice. I would give him a try.

Hayters web site has different parts lists with exploded diagrams that may also be useful.

I have linked to another site that also has older manuals as well.

Mower Magic Ltd Mower Magic Garden Machinery Lincoln

✅ The UK's number one for lawnmowers and garden machinery. Shop lawnmower, chainsaw, leaf blower, grass trimmers, hedge trimmers and much more at Mower Magic.

www.mowermagic.co.uk

Link to the manual and parts list for a 306R

305R, 306R & 307R Parts Diagram - Hayter HARRIER 41 Owner's Handbook Manual [Page 43]

Hayter HARRIER 41 Manual Online: 305R, 306R & 307R Parts Diagram. 1.41 2.305R/306R/307R (A) 14...

www.manualslib.com

 

[mikej2005]

Can you shift the central bolt and let us see the state of those washers please?
Some systems used washers to tension the belt, others had a belt that rode up the pulley to increase the mowing speed.
For sure, make sure the belt you have is the correct one.....it’s section will give us a clue.
John

Thanks for the reply. I've taken the pulley components apart and the washers all appear to be fine, but the pulley halves (which should be identical) are both showing signs of wear to their outer surfaces, which may go someway to explaining how loose they are.

This is the outer pulley half with the indentation caused by an adjacent washer that also fits around the drive-shaft...

...and this photo shows indentations on the outer surface of each, for comparison. The inner pulley half is on the left, with an indentation caused by the part of the drive-shaft it butts up to. Note that the indentations are not identical, so aren't part of the pulley design and must have been caused by wear and tear. The washer in-between is the washer that sits between them.

While the indentations don't look like much, it may account for a good few milimetres of play in the system. Here's a photo with the bolt and outer washer removed and the remaining pulley halves and spacing washers pushed hard up against the opposite side. which shows a gap of around 4-5mm which is why they're so loose.

I'm thinking it might be worth buying two new pulley halves ? They are still available and relatively inexpensive (£6-8 each)

 

[mikej2005]

The halves of the pulley are meant to be loose but I dont think they are that loose. If you type intoyou tube “micks mowers hayter drive” you will pull up loads of videos that show different drive issues and how to fix them. Mick also does a live stream on a Saturday night at 6.30 where people ask for advice. I would give him a try.

Hayters web site has different parts lists with exploded diagrams that may also be useful.

I have linked to another site that also has older manuals as well.

Mower Magic Ltd Mower Magic Garden Machinery Lincoln

✅ The UK's number one for lawnmowers and garden machinery. Shop lawnmower, chainsaw, leaf blower, grass trimmers, hedge trimmers and much more at Mower Magic.

www.mowermagic.co.uk

Link to the manual and parts list for a 306R

305R, 306R & 307R Parts Diagram - Hayter HARRIER 41 Owner's Handbook Manual [Page 43]

Hayter HARRIER 41 Manual Online: 305R, 306R & 307R Parts Diagram. 1.41 2.305R/306R/307R (A) 14...

www.manualslib.com

Thanks for that. Yes, I've been watching some of his videos although I haven't yet found one that features a Hayter mower with the split-pulley design. I have picked up tips on how to change the height adjustment bar though, which has just broken on mine !

Thanks for the link to the manual. Interestingly, that manual is for later versions of the Hayter 41 306R (1999 onwards) and it looks like they moved from the split-pulleys found on my 1997 model (Part no. 306104) to a one-piece drive-shaft and fixed pulley on the same model from 1999 onwards (Part no. 306123).

This could be an indication that they had problems with the split-pulley system but it's hard to judge whether I could retro-fit the all-in-one option. That said, the pulley halves seem to be fairly readily available and inexpensive (£6-8 each) whereas the all-in-one option is expensive (£50-60) and less readily available, plus it could be tricky to fit as it would involve removing a driveshaft roll pin, which looks pretty inaccessible.

 

[mikej2005]

FWIW, this is the old belt - I cut it off years ago due to not being able to push the mower when auto-drive wasn't engaged, no matter how I adjusted it (I presume that it had stretched or worn down, meaning that I had to adjust it so far to one extreme in order to get it to pull that it was still partially engaged when the lever was released, giving far too much resistance and making pushing it manually almost impossible).

When the old belt is pulled tight temporarily around the pulley, the pulleys are still slightly loose and the belt sits so far down in-between them that it must surely be touching the washer that goes in-between the two pulley halves.

 

[Burnerman]

For the life of me I can’t see why that pulley needs to be split.....unless that’s the only way to get the belt on!
The diagram seems to show a tensioner which will keep the belt tight enough.
I also don’t understand why the pulley halves seem to have three quadrants - unless they were originally sprung.
With regret I’ll bale out of this one as I’m only guessing which isn’t helpful.
I’d love to know how you get on!
John

 

[Burnerman]

Looking at the pics again, maybe my comment about actually getting the belt on may be correct? Access looks pretty tight.
John

 

[mikej2005]

Yes, there doesn't seem to be a gap big enough to take the belt off without needing to remove the outer pulley half. It's hard to tell from the photos on the online listings, but it's possible that the (later) all-in-one pulley option was a bit smaller, which would allow for belt replacement without needing to be removed. There are definitely no springs in that part of the auto-drive system - it's just two pulley halves and two washers on the drive-shaft, with a bolt and outer washer holding them on.

I don't know much about these mowers but I think that the drive-shafts spin all the time on certain models and that the auto-drive lever simply pulls on the small tensioner wheel near the back roller, which pulls everything tight. I'm not really sure how this works, TBH. The pulleys are definitely free to spin on the drive-shaft, so the auto-drive system would need to be under a fair amount of tension in order to work, which was why I was thinking that the V-shaped belt would be forced down between the two pulley halves and push them outwards and up against the adjacent surfaces, providing the friction needed.

 

[Burnerman]

A cable operated tensioner used to be reasonably common on the Qualcast cylinder mower.....the belt was very slack at rest and yanked up to engage the drive.....maybe yours is similar looking at the cable on the left handlebar.
I have come across this sort of power take off on other Hayters, but they were chain drive.
A vee belt is meant to drive on its flanks, so maybe a replacement pulley would be a good move.
Is the rest of the machine in good nick?
John

 

[mikej2005]

A cable operated tensioner used to be reasonably common on the Qualcast cylinder mower.....the belt was very slack at rest and yanked up to engage the drive.....maybe yours is similar looking at the cable on the left handlebar.
I have come across this sort of power take off on other Hayters, but they were chain drive.
A vee belt is meant to drive on its flanks, so maybe a replacement pulley would be a good move.
Is the rest of the machine in good nick?
John

Yep - think it's looking like I'll need to replace both half-pulleys and get a new belt.

Apart from a snapped height adjustment bar (which looks like a common problem on these mowers, but a fairly cheap and reasonably easy fix), the mower is in pretty good shape and the Briggs and Stratton engine has worked flawlessly since 1997. The only thing I've needed to replace on it was one of the cables (clutch, I think). I've been neglecting the servicing a bit though, so will give it an oil and filter change while it's out of action.