Steering worm and gear wheel
 

I am looking for a steering gear and worm wheel for an 8" scale Burrell tractor. I have looked at the dimensions of one for a 6" Savage and as the gear wheel is 3.687" across the teeth, it is possible I could adapt this. Has anyone got anything of similar size?
I am in fairly urgent need as I cannot steer my engine at the moment and the cost of having one made to the current specification is prohibitive.
Has anyone got anything out there that I can consider please?

Please see my reply to your previous thread. Without the information I requested I, or anybody else, cannot really help you.

Cheers
Carl.

Does the 6" devonshire one not fit? maybe worth speaking to adrian

Thanks for your reply Carl. The gear wheel is 2 1/2" across the teeth with a shaft size of 1 1/2" It has 25 teeth and the worm wheel turns 20 times for one complete revolution of the gear wheel ( not sure how you would work out the ratio). The worm wheel on the steering shaft is bored out 5/8" diameter There is room for a bigger gear wheel up to 3 1/2" and the centre could be machined to fit the shaft. I realise I am not going to get an exact match to the original but I am hoping that someone has something that could be adapted to fit.

Michael

Hi Michael

I have a few small worm/wheel gearboxes. I'll root them out and see how the dimensions of the gears compare with those you have given.

Cheers
Carl.

That would be great Carl, thank you.

Hi Michael

I have looked through the gearboxes I have. The closest ratio I have is 30:1, not the 20:1 you need. My other boxes are 60:1 and 120:1 - not in the right ball park.

I have had a look through various suppliers of stock gears. Judging by the sizes you have given you need to source gears of 2.5 or 3 Mod - or imperial DP equivalent. I suspect metric/Mod will be easier to find and cheaper.

This company is worth looking at :-

https://www.rargears.com/gears/worm-wheels

This website gives the dimensions of wheels/worms they supply. Assuming your existing worm is single start, your wheel must be 20 teeth to give you a ratio of 20:1. However you state it has 27 teeth, so something doesn't tally here.

Don't forget you also need to confirm the 'hand' of the worm - get it wrong and you will be turning the steering wheel anti-clockwise to steer to the right! Incidentally, a friend had a Series 1 Landrover which had opposite hand steering ! An interesting driving experience !

Is the drawing available? If so, what are the original specifications?

Sorry that I can't help you directly.

Regards
Carl.

Hi Carl,
I appreciate your help. I will have a look at the quoted website and see what they have. Sadly there are no original drawings for my engine. Your friend with the Series 1 Land Rover had an interesting time! Some years ago I was operating a Fowler ploughing engine named Margaret built in 1870. You steered it from a step outside of the footplate using a vertical shaft and this steering wheel had to be turned left to go right etc. much concentration needed!

Thanks again

Michael

He drove the Series LR like that for 5 years, even passing 5 MOTs. In those days the driver used to stay in the car during the test, helping the tester - so it went unnoticed.

Good luck with sourcing a worm/wheel.

Regards
Carl.

Is "3.687" across the teeth" the diameter?


You may be able to use a stock spur gear and make a worm to suit.

The spur gear would need angled teeth , as on a Fowler .

Not necessarily the worm could be set over at its helix angle.

Yes , but not on a conventional traction engine , where the plane of the steering shaft is at a right angle to that of the chain drum .