[SirAlec]

I wanted to share with you guys how wheel servicing of a behemoth 2515 is done.
Well this fete is not done by me, but by a mechanic friend Sajjan Singh. He runs a road side Highway garage on NH 14. Initially from Bharatpur, He had been fiddling with trucks all his teenage years as an apprentice to veteran mechanic who were champs of 312 or 1210D. In short he is pretty good at what he does.

This truck was sitting duck for the past 10 months by the virtue of its stingy owner. Suddenly he decided to make use of this and found the wheels making strange sounds.

Enjoy!

Such a beautiful machine in such a state, Shame on the owner.


Wheel Hub




Hub Cap removed


Thats a No.50 socket with a modified cross wrench.


Now its clear why it was modded so, The leverage that this rod create is so much, that opening this bolt is like cutting a butter with a hot knife.


Look at the size of the Hub. This hub houses two bearings of different size.


removing old grease and cleaning with diesel




Hub fully serviced with fresh grease.

[SirAlec]

Continued...

Brake Shoe. The cost varies from Rs.600 per pair all the way to Rs.1800/-
Compare that with a normal sedan that costs about Rs.1800 per pair.
Thats a beauty when a vehicle is sold in large quantities and parts is interchangeable across the range.



The actuator, This is how the shoe is activated and the wheel is jammed there and then when applied.
A piece of advice " Never tailgate a lorry" even if you have a Beemer loaded with, all those fancy ebd, abs etc etc



THANKS for reading.


Slave drum







Old brake shoe


Tools, simple but very effective. These practical mechanic buggers never uses those fancy pullers and stuff. All tools are made to order according to their need.




This is a neatly home made jack to lower the engine and gearbox of a truck. Cost him a whole Rs.2500 to make as per his specs at a local iron wala.

[julupani]

The truck is in a particularly bad state of neglect I have to say.

To add to the advice of never tailgating a lorry, never ever tail gate an empty lorry if you can spot one or never even get close to the rear of an unbuilt chassis. Because of the heavy variation in load, when the brakes designed for a 25tone GVW vehicle have to deal with just about 7tons, they become very very effective and with some modern trucks coming in with ABS too, no matter how many different acronyms u add to a sedans list of features, there is no beating a large brake on an unladen truck.

[BaCkSeAtDrIVeR]

The rear wheel servicing is even more colourful - literally.

Sometimes, the grease (bearings) and oil (diff) may mix due to failed seals, heat, etc, and become yellow.

And the task of removing the wheels, bearings, etc and putting them on again itself is worth a video. They will have really huge wrenches and use 3/ 4 inch pipes for leverage.

That thingie to remove gearbox / engines is available off the shelf AFAIK - no need to fabricate one. It is raised up and supports the gear box as the supports / mountings are loosened; and then the thingie itself is lowered, and with it comes the gearbox.

For the engine, IIRC, they use a crane like thingie to pull up the block and back out the crane to remove the block. The block / chassis mounting is designed such that it cannot be lowered. At least, with the older design.

[condor]

@SirAlec, intresting posts there. Thanks !

One question: how does the actuator work ?

If I were to look at the actuator alone, then the action on it by the two brake shows (see pic below) can jam the wheels.



But when the brakes are applied, the first thing that should happen is the brake shoes moving outwards to create fiction (see #1). If that happens, then the pressure on the 'S' shaped part is opposite (opp of what I have shown in the prev pic) - see #2 in pic.



So how does the braking work ?

[SirAlec]

Well! honestly, i have no idea. Will have a clear picture only when i have a hands on with slave cylinder and the back shaft of this actuator.

[julupani]

Well let me try and explain how the brake actuators works.

1st of all, consider the brake actuating mechanism. Behind the actuator that you see here is a lever. This lever is caused to be rotated by air-pressure, causing this actuator to rotate.

When this actuator rotates, the brake shoes move. But the shoes can move only along the diameter.

When the brakes pressure is released, it is the large sized spring that you see in the middle causes the brake shoes, and the actuator to return to its original position.

As for the jamming thing you have mentioned, I actually could not get what exactly you meant. If you could have a go at explaining again, it would be helpful.

[condor]

@Julupani, thanks. That makes more sense.

So in the second pic in my post, the sequence of action is #2, followed by #1. The actuator moves such that the brake shoes are pushed outward.

[julupani]

Yes, you got that right. The pic below is the lever that actually rotates the actuator.

http://www.team-bhp.com/forum/attach...e-cylinder.jpg

[Ashley2]

This is called S cam type.
Almost standard on many trucks and buses

[Mr.Boss]

OT: I could find the shock absorbers are disconnected from the front axle. This is a common practice among truckers, even this scenario can be observed in many government bus rear axles. Is there any advantage of this practice?
IMO this affects the damping effect of suspension and a bit in roll stability too. Could someone throw light on this?

[Ashley2]

Originally Posted by Mr.Boss

OT: I could find the shock absorbers are disconnected from the front axle. This is a common practice among truckers, even this scenario can be observed in many government bus rear axles. Is there any advantage of this practice?
IMO this affects the damping effect of suspension and a bit in roll stability too. Could someone throw light on this?

This is because of poor maintenance and nothing technical about it!