Crown Wheel Question

[Nick Salmon]

The general wisdom today that A7 back axles are 'difficult' leads me to ask how Austin managed to churn out hundreds of them each month. Did they have a team of people well-versed in the dark art or was there some sort of mechanical measuring setup that speeded up the process?

[Ruairidh Dunford]

There was, it was an offset dial (see below, from the Service journals)that you turned to match the engraving on the end of the pinion which you then shimmed until the pinion touched that point of the tool.

Once the pinion and crown wheel, spacers etc. are worn, the tool is not really very effective and experience/measuring/blueing up comes into play.

   

[MatthewMyerscough]

Hi Everyone,

Ian, I understand your point, I think in my case the wear isn't that bad on this bearing, there are not ridges or imperfections in the outer race just a slight polished sheen where the rollers have been running (I thought I had a picture to upload but sadly I don't). My Dad has had a chance to mess with it today (normally I only get chance at the weekends). He added in an extra 5 thou shim and tweaked the adjusters to alter the mesh and it seemed to run smoothly with the backlash set. He reckons it is still on the edge of the teeth but it is wiping further up them now. Annoyingly, he didn't take any photos but he hasn't altered anything since so I should be able to get some for comparison.

Terry & Nick - it certainly is a 'dark art' and very daunting but I've always liked a challenge as I'm keen to learn. I like doing as much as I can myself and luckily my Dad is very technically and mechanically minded so its good experience. 

Ruairdh - I think Chris KC has that very tool, its interesting to know they are still around albeit not necessarily useful any more. My pinion is etched with 26 and 1512Y.

Thanks

Ruairi

[Ruairidh Dunford]

Chris is a lucky guy, would love to see a real one in the flesh.

The Cornwall A7 Club made some, about 20 years ago, I think.

[Chris Garner]

I am unable to answer how the AMC managed to build the several hundred a month with such accuracy and how many were employed to do so. They obviously had the correct tooling and gauges and experienced operatives with years of experience. However, I can offer some insight into how the back axles were built up in the late 1920s.

Information is sketchy so bear with me!

Chassis assembly, gearbox and engine production, axles, radiators etc were all carried out in the South Works, and what is described below is the Chassis Erecting Shop.
The Seven section was adjacent to both the Twelve and Twenty assembly areas.

Rear Axle:
The rear axle tube ends entered the shop together with the rear axle casing, the latter being directed to the final rear axle assembly area. The tube ends were then brazed to the axle. Further brazing of the torque tube is performed and the whole assembly is passed to the assembly bench to marry up with the rear axle casings ( above ). In the same area axle shafts, hardened pinion bearings, spindle, gears were introduced and the whole built up on the final assembly benches. Adjacent to these were a series of test stands.

Elsewhere in the Works were the manufacturing of the chassis parts, machining section and frame drilling. The parts were then conveyed to an area adjacent to the front and rear axle sections where they were assembled and placed on the frame building track. Steering boxes and associated components were built adjacent to the front axle assembly area.

Engines were assembled on a floor above and delivered to the test section by means of a conveyor passing through the floor. After test, the engine was married to its gearbox ( built elsewhere ) and then fan and prop-shaft added. The whole unit was then fitted into the chassis on the track with the universal joint coupled up.
Wheel assemblies were built up nearby with a chute for delivering tyres and tubes, wheels built, stove enamelled and tyres fitted. The last operation was fitting to the hubs. The whole rolling chassis then exited the area into to the body section. ( It appears the exit was between the women's lavatories and the tool stores! )

Just a brief insight!

[Nick Salmon]

Many thanks to Ruairidh and Chris for the insights.

[Chris KC]

Ruairdh - I think Chris KC has that very tool, its interesting to know they are still around albeit not necessarily useful any more. My pinion is etched with 26 and 1512Y.
Ruairi

He does indeed! - only one I've ever seen.
   

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Chris is a lucky guy, would love to see a real one in the flesh.

Ruairidh, drop in next time you're passing & I'll swap you a viewing for a sip of French whisky!

[Ruairidh Dunford]

C'est une affaire!

[MatthewMyerscough]

Chris Garner - Thanks for that information, its really fascinating, I bet every part of the process was carefully timed as well.

Chris KC - I meant to ask you on the other thread, out of interest how did you come by it? I'd imagine it wasn't in every mechanics toolbox in its day.

Hopefully I'll have some progress to report on my axle this weekend.

[dickie65]

It looks like to much blue was used.
A look at the pinion end as well as the crownwheel will help.
My back axle was set up using a gauge which might well have been an original Austin one Borrowed from a fellow owner and fettler.
Best of luck with your setting up
At least we have quite a lot of adjustment on our axles to vary the pinion engagement with the shims then sideways mesh adjustment on the castle nuts.
Have you tried fitting the crownwheel in a different bolt orientation to se if the runout can be reduced.
It only takes a tiny bit of dirt or a burr on a hole edge to cause run out.