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Brake Cross-shafts - Definitive notes.

After reading all I could find on said shafts, I am now totally confused, and think we need a thread that provides definitive information on each iteration.
The shaft fitted to my ARQ has a pin spanning the inside of the tube, 9" in from the OS, and as the photo shows, that pin appears to lock both tubes together.

I've just given the underside a coat of paint.

Overhead:


Overlap of the two shafts:


I have started another Thread concerning lubrication of the bearings, with a link to the Model Engineering Forum where I posed the problem of the lack of provision, and it's generating interesting suggestions.

Geoff - Watching paint dry

Edit:
Should the OS bearing be capable of swivelling, as the other two, or be 'locked' as mine is?

Location: South Norfolk - Next to Suffolk

Re: Brake Cross-shafts - Definitive notes.

Hi Geoff

Many must know the answer but have not responded. It is the one part of my car never dismantled; only recently found it under all the caked oil and mud and all those immovebale bolts or cotters seemed to promise hours of work on my back if forced! I understood the tubes were welded together.

The circa 1932-35 cross shaft is one of the items least adequately explained or illustrated in most sources. Motion is transmitted from the pedal to near the centre then outward again via the inner tube to each side, the idea being to equalise torque. As the relative motion of the concentric tubes on the rhs is not apparent, It takes a rare genius lying under the car and contemplating the goo encrusted bits to fathom the working (or more correctly the intended working, the two tubes often being all locked solid).

Is the pin the link, or a back up, or an addition?

Location: Auckland, NZ

Re: Brake Cross-shafts - Definitive notes.

I have never had very much to do with the later brake cross shaft (which doesn't seem to preclude anyone commenting) but there are drawings of the assemblies in both Woodrow and The Companion.
Not very helpful I know.

Tony.

Re: Brake Cross-shafts - Definitive notes.

Hi Tony

The illustrations are for the Girling model, the operation of which is fully fathomable by inspection, as the concentric tubes clearly move relative each other.

Bob Culver

Location: Auckland, NZ

Re: Brake Cross-shafts - Definitive notes.

I am afraid that I fail to see the problem, the assembly is not complicated and is well described in a number of publications. It works as intended provided the inner and outer tubes don't seize through lack of maintenance, separating them by removing the peened pin/plug weld can be a bit of a mission but doable with care. The spherical bearing carriers should move but be tight in their pressed mounting brackets, the zinc insert is the bearing not the spherical carrier. The only other part of the assembly is the central handbrake adjuster but the operation of that should be fairly obvious to most.

Location: NZ

Re: Brake Cross-shafts - Definitive notes.

Well Geoff, looks like you have the answer at last.Can it be taken from the answers that the pin is the only device preventing rotation of the tubes? Surely some expert could have answered promptly.
Not all newcomers access all the publications and websites. Woodrow for example I do not recall describing the operation. I doubt if you would find one modern mechanic in 10 who could fathom the full intended operation of the concentric tubes within 15 minutes by examination of a dirt encrusted system.
No particular maintenace operation is specifically intended to stop the tubes rusting together.

Bob Culver

Location: Auckland, NZ

Re: Brake Cross-shafts - Definitive notes.

Geoff,

as far as I am aware there should be a whole load of clips, felts seals and discs attached to your cross shaft - their purpose is to keep crud out and lubrication in?

If you need photos of the correct set up let me know.

Re: Brake Cross-shafts - Definitive notes.

Thanks for the responses.
I had read that there is either a small amount of radial movement between the tubes, or none at all when welded up as one, hence my confusion and request for info.
If the former, then I assume the pin moves in short slots in the inner tube.
The tubes on mine are not welded together, and without any of the protective gubbins Ruairidh mentions, must assume rusted solid.
Wonder how long Plus Gas will take to free them?

Ruairidh,
The shaft was fitted as seen in the 1st photo, there being neither hide nor hair of the parts you mention, or as shown in the Companion, so will take you up on your offer please, with thanks.
Without those bits and pieces, your use of heat shrink tubing should work, or I make a pair of leather 'stockings'.

Geoff - Info about caster, wedges and Ball Flange next just to keep everyone on their toes

Location: South Norfolk - Next to Suffolk

Re: Brake Cross-shafts - Definitive notes.

My mistake Geoff - the parts I recall are from a late car - I will still post pictures for interest. Crud prevention ideas may come from them!

I must admit that I have had very little problems with cross shafts over the years, despite some of them appearing parlous.

Most are constantly bombarded with oil from the engine and gearbox etc. - this probably lubricates them quite sufficiently I imagine.

Re: Brake Cross-shafts - Definitive notes.

Geoff Halstead

I had read that there is either a small amount of radial movement between the tubes, or none at all when welded up as one, hence my confusion and request for info.
If the former, then I assume the pin moves in short slots in the inner tube.
The tubes on mine are not welded together, and without any of the protective gubbins Ruairidh mentions, must assume rusted solid.
Wonder how long Plus Gas will take to free them?

Geoff,

The concentric tubes are designed to solve the tendency of the earlier shaft to twist by bringing the brake pedal force to the centre of the assembly. The brake pedal is attached to the outer tube, this is pined to the inner tube as you have discovered, there is a zinc bearing in the other end of the outer tube which allows the inner tube to twist under load. No slots of other complications, the only issue comes when the two tubes completely seize together with rust. If you remove the zinc bearing, stand the shaft on end and apply Phosphoric Acid between the tubes this can help free things, It will need a very thorough soak and flush afterwards to remove the acid.

Location: NZ

Re: Brake Cross-shafts - Definitive notes.

Some may have become curious as to what is fitted to their early 30s car. Timing is not clear even from the extensive change list in the Companion and variants are not or not well distinguished in Williams or Woodrow.
Now that cars are pristine identification is relatively simple but
1. Unitary, identifiable by a one piece forging on the rh end. (off side in Pom speak)
2. The model with somewhat obscure concentric tube, identifiable by two separate forgings on rh end.
Considering how far the common pinned point is from the centre, seems an awkward “solution”. Maybe the springiness each side was tailoreded to match. A single 2 inch water pipe may have worked better, but the concept of a solid pedal was presumably far fetched at the time. might be even more disconcerting when nothing much happens!

There is also the types which accompanied Girlings, identifiable by the balance device incorporated in the dangling mid car lever.

Bob Culver

Location: Auckland, NZ

Re: Brake Cross-shafts - Definitive notes.

Geoff,

for interest only as this is a Girling cross shaft:

 photo EDF09EA8-B942-4ECA-B0FC-911FB50139C5_zpslhwhlcvh.jpg

 photo 6263B9BD-F215-4FC8-A44C-9F0C8233D7F8_zpsp5qles6b.jpg

 photo 803FD9B4-7977-4748-91A0-2ED09B9B3CC4_zps4czcnujk.jpg

Re: Brake Cross-shafts - Definitive notes.

Just as well Geoff did not resolve his questions himself. Presumably others have found replies to this and realted post as interesting as I have. Particularly Hedds observations. Also bemused by Jims mod in the older Seven tradition. If he wraps the shaft with brass and hose clips he can just move it along every 10 years!

As a matter of curiosity just when was the concentric cross tube introduced?
The lack of rigidity of the brackets has been identified by several and is mentioned in the Williams book so is not obscure, so it seems surprising Austin did not beef these.
I am surprised how effective the concentric set up apparently is. With forward movement on the rhs, it seems the logical place for the lock pin might be at or near the lhs, and certainly not right of centre!

For years when working under the car I had idly puzzled over the construction, but there were more pressing concerns. I only read the explanation recently, possibly in the Companion. Certainly not in Pitmans, the only guide for decades. Nor Nicholson, or Williams (or modern Woodrow). Just where does the explanation of the concentric tubes appear?

I spent a day chisseling 80 years of caked goo and emerged like a candidate for the B&W Minstrel show; the construction was then somewhat more apparent.

Bob Culver

Location: Auckland, NZ

Re: Brake Cross-shafts - Definitive notes.

"I spent a day chisseling 80 years of caked goo and emerged like a candidate for the B&W Minstrel show; the construction was then somewhat more apparent."

I take it that you are now recommissioning the car then Bob, we will look forward to seeing it out on club runs.

Location: NZ

Re: Brake Cross-shafts - Definitive notes.

In reply to Bobs comments.

The earliest cross shaft I have been involved with is a 1928 item on our GE cup. The brackets/bearings are simply a bit of tin wrapped around the shaft. Very flimsy. But typical Austin value engineering. This is obviously uncoupled.

My 1930 RL is the first of the coupled cars. It has the plummer block type bearings, but the steel brackets that fit onto the chassis have only 4 fixings a side. But also a centre bearing. The chassis bearing brackets are best described if you were to cut the front and back off the ruby items already pictured. Clearly 'beefed up' since 1928, yet really quite flimsy. The centre bearing of course adds some rigidity.

I assume (perhaps incorrectly) that the concentric tube improvement came about with the long wheelbase cars in late 1931. These had, or at least the one fitted to fathers 1934 RP had the style of chassis mounted bearing bracket as fitted to Geoffs Ruby, 'beefed up' again if you like.

When doing fathers 1929 uncoupled chummy, which had been much modified by a cretin, we fitted a custom solid shaft in the late style bearings. Our preference was to keep to Austin parts and style.

Re: Brake Cross-shafts - Definitive notes.

Ian,
That zinc bearing is in tight!
Advise needed please on removing it.

Ruairidh,
Thanks for the photos.
My later front axle is fitted with Girling brakes.
Haven't checked the rears yet.

Bob,
I posed the question hoping to get as much information as possible in one spot, and it certainly has not been in vain.
With luck, this thread will become the Definitive Notes on the subject for all to read, old hands as well as newcomers.

It was Ian's post that had me saying "Of course!"
I, and no doubt many others, now know how it works - Thanks Ian.

Geoff - Thanks all for your input

Location: South Norfolk - Next to Suffolk

Re: Brake Cross-shafts - Definitive notes.

Hi Geoff, I guess have you tried heat and plenty of penetrating oil, if it is that tightly in there perhaps it is best left alone. If you wreck the bearing in your attempts and still fail to remove it you then have to dismantle the entire assy, which is a pain in the proverbial. Are you sure that yours is seized, have you applied a lever between the two off side arms and looked for movement? It is only very slight, there is almost more spring in the arm than the shaft.

Location: NZ