Thwaites Nimbus Dumper Gearbox

[Andyinfrance]

Hi all,

Need a little help in defining the gearbox on my Thwaites Nimbus Dumper as the output shaft oil seal is totally shot (see photos). Looks like it has also had some rework as the upper casing has been welded in the past. Also need a service / parts manual for this gearbox as the gearstick cover is missing so would like to get a new part (if possible) plus it’s jumping out of gear or sticks in gear. So I think I need to strip it down to check the selector shaft / springs

Any help or advice would be appreciated, once the gearbox is done need to fix the Salisbury axle hub oil seals

Thanks

Andy

[dixie-normous]

Try these guys, apparently very good and export parts too
John
http://davidcornwallis.com/index.php

[Andyinfrance]

Hello all,
Can anyone tell me what type of gearbox I have on my Thwaites Nimbus dumper as I’m looking for a manual for it.

[essexpete]

I wonder if it might be worth having contact with this company?

https://www.pesplant.co.uk/product/thwa ... m-gearbox/

Probably the cheapest option will be to keep your eyes open for a simple 3 speed out of a breaking dumper. Yours looks to have been ''got at' but all the old gearboxes and steering boxes have a tendency to water ingress and tend to be knackered by that.

[Matchless?58]

Think that is a newage 40m gearbox . Same one in my Orion dumper . Welding looks absolutely rough

[MrF]

123roulement do seals & bearings in France mail order, Ive used them for the odd thing, it comes fast with no fuss. :-
https://www.123roulement.com/rubrique/joint-rotatif
Whats the bearing like behind the seal? sometimes if you find a wrecked seal, the bearing behind it is the culprit.

The welding looks rough, but a cast iron casting is a pig to weld and stress cracks on cool down, and the whole thing has to be heated evenly in a oven prior and post weld and left to cool over several hours with peening, so the tacks are probably a attempt to just hold it enough without getting masses of heat into things then relying on sealer to do its job. So if that cover is still on not causing issues and just the seal is leaking, I think I'd be cleaning it up of grot and putting a bead of devcon or belzona over the weld area rather than wanting to redo it.

[essexpete]

I am not sure about the make, but most of the Newage boxes I have seen have a flat top with the lever cone/housing part of the removal top.
It is over 40 years since I took apart the gearbox on our 60s Nimbus, I really cannot remember.

[Andyinfrance]

I wonder if it might be worth having contact with this company?

https://www.pesplant.co.uk/product/thwa ... m-gearbox/

Probably the cheapest option will be to keep your eyes open for a simple 3 speed out of a breaking dumper. Yours looks to have been ''got at' but all the old gearboxes and steering boxes have a tendency to water ingress and tend to be knackered by that.

Thanks for the feedback, all the gearboxes i have seen are quite expensive but will check out eBay. I’ve been in contact with David Cornwallis and he has new seals although no price at the moment

[Andyinfrance]

Think that is a newage 40m gearbox . Same one in my Orion dumper . Welding looks absolutely rough

Hi, I thought my dumper was an Orion but after seeing pictures of an Nimbus, its definitely an Nimbus which I recon is around early 1960’s. Welding is bad and watergascenteredvtge Bixente, but hearing seem ok

[Andyinfrance]

123roulement do seals & bearings in France mail order, Ive used them for the odd thing, it comes fast with no fuss. :-
https://www.123roulement.com/rubrique/joint-rotatif
Whats the bearing like behind the seal? sometimes if you find a wrecked seal, the bearing behind it is the culprit.

The welding looks rough, but a cast iron casting is a pig to weld and stress cracks on cool down, and the whole thing has to be heated evenly in a oven prior and post weld and left to cool over several hours with peening, so the tacks are probably a attempt to just hold it enough without getting masses of heat into things then relying on sealer to do its job. So if that cover is still on not causing issues and just the seal is leaking, I think I'd be cleaning it up of grot and putting a bead of devcon or belzona over the weld area rather than wanting to redo it.

Thanks for the contact I will contact them for the seals. I’ve not checked the bearings behind the seal yet, that’s my next job once I removed the output shaft castle nut!
For the welding I plan the remove the old welding attempt and re-weld with cast iron rods ensuring I only weld about an inch at a time and peen as it’s cooling. It needs redoing as it’s leaking water into the box. Devcon would also be a good fix which I might use after the welding attempt.