The Bridge at Dozan, Bolan Pass, near Quetta, Pakistan

The Bridge at Dozan, Bolan Pass, near Quetta, Pakistan
The bridge carried both road and rail over a creek bed. The bed had to be dug out by hand over many days, with much help freely given by locals. Click on the photo and scroll down, to bring up the story of this bridge. Go to: to find more.

Tuesday, August 30, 2011

Now, for the Rear Axle ......

As many would be aware, our old trucks and buses can be very slow by today's standards, and this was definitely the case for Albert. The decision was made to increase Albert's road speed to help keep up with today's speed; nobody wants to be stuck behind an old bus, right? Andy is currently working on the installation of a higher ratio differential which, when combined with the previously fitted 2 speed transfer box, will allow a top road speed of 50mph (80kph)...”vital for safe driving on European motorways and trans- Australian highways!” explained Andy.
With a higher ratio it means that even though the engine speed may remain the same, the rear wheels turn faster, so the bus goes faster.
The 2 speed transfer box (silver case, looking to the rear of the bus. When its higher speed is engaged, the wheels turn 30% faster than normal. So instead of doing 40 mph, the bus (theoretically, and if you are brave enough) can do 53 mph. (83 kph!)


On close examination the rear axle was found to be in quite good condition.

Andy, head down tail up, cleans off the diff. after taking off the top cover.

And the greatest surprise of all was that it was already the higher ratio: how could this be?? According to all the known wisdom, Sydney Albions were limited to 32 mph by having a 6/24 axle ratio. (don't worry about remembering that). Albert has a 5/27 axle: photographic evidence:

Can you see it? At centre LHS, stamped into the casing is 5/27 (click on the photo)
Further proof, as if the stamp on the case could be wrong! There it is, stamped into the pinion itself: 5/27.

The innards of the axle: the worm drive wheel and inside it, the differential.
The bronze wheel is in lovely condition despite thousands of miles on rough terrain, and the passage of 40 years since it was last looked at. A caliper is used to check the wear on the teeth of the bronze pinion: only 0.26 mm. wear after 50 - 60 years! A brand new pinion was measured and found to be 8 mm. at his point.

As an aside: this question of the axle and its ratio must have generated about 20 emails: there was much discussion on just how a bus supposed to be capable of 32.5 mph maximum governed speed, could now apparently do 40 mph!

With this work on engine and driveline underway, work also began on the new floor to the top deck, complete with fresh wall panelling and a splash of brightly coloured paint.

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