Truck & Bus Forum - TK mystery part

Truck & Bus Forum (https://www.truckandbusforum.com/index.php)

- Vintage Truck Discussion (https://www.truckandbusforum.com/forumdisplay.php?f=7)

- - TK mystery part (https://www.truckandbusforum.com/showthread.php?t=4637)

Quote:

Originally Posted by coachman (Post 14613)

One for G-C, am I correct in thinking that some TKs also had a starting handle clipped up under the cab. I don't think it could actually be used to start the engine but was used to turn the engine over if needed during servicing or repair, for example when adjusting valve clearances ?

Indeed you are correct on all counts.

The small (214 cu in petrol) was really just a car engine.

There was a 'keyhole' in the front bumper - click on the following then click on the image to enlarge it then look above the first 7 on the front number plate:-
http://upload.wikimedia.org/wikipedi...xtra_shine.jpg

The hydraulic jack supplied as standard (unless there was a delete code added) was a quality product (it had to be to lift a possibly laden truck for a wheel-change).

Can you explain a bit about how the air brake foot valve works? It has two air supplies from two independent tanks and two pipes to the servo on the master cylinder. I'll grab a picture if you need it.

Quote:

Originally Posted by mylesdw (Post 15251)

A dual-air footbrake system provides a safety feature (the system will work if either of the circuits fail). Likewise, the hydraulic master cylinder is split so that failure of either circuit will provide at least 'residual braking' for the vehicle.

A diagram:- http://lh6.ggpht.com/_Ii1ukGkfijY/Sq...jpg?imgmax=800

Quote:

Compressed air from the compressor is stored in a wet tank in a semi-dried condition.
It then flows to the multi-circuit protection valve, which divides the feed to serve the two service reservoirs.
Simultaneously, pressurized air from the reservoirs combines through internal passages in the multicircuit protection valve to operate the remote spring brake actuator through the hand control valve.
Two service lines are connected to a tandem power cylinder controlled by a dual foot valve.
This arrangement maintains air supply to the other circuit in case of a fault develops in one service line.
The power piston push rod pushes the tandem master cylinder hydraulic piston forward so that the air pressure is converted to hydraulic pressure.
The hydraulic fluid supply is divided into two circuits to serve the front and rear brake expander cylinders.
In dual air and hydraulic line systems, both systems operate independently thereby safeguarding against failure of one or the other circuit.
The hand control valve is used only to park the vehicle. When the hand control valve lever is moved from ‘off to ‘park’ position, air from the remote spring actuator chamber is exhausted. This allows the power spring within the actuator to expand and provide maximum pull to the rod linkage of mechanical parking brake.

From:- http://what-when-how.com/automobile/...em-automobile/

Does that answer your question - or would you like a more detailed explanation?

More detailed if possible please, particularly the TWO air lines to the servo. Does it use air pressure in both directions, like a double acting ram for applying AND releasing the brakes. The two ports on the servo are in quite different places, one in the end of the cylinder shape and the other about half way along on the circumference.

See above - come back if you still have questions.

Here's a rather crappy picture but it shows the two airlines going into the servo.

One airline feeds the 'front' piston and therefore has to be positioned halfway along the servo body whilst the other airline feeds into the end of the servo body and feeds the rear piston.
Because of the design of the pistons within the servo, each of the air supplies can operate the master cylinder.

Brilliant! I understand now. There is a further question I have about the hand brake circuit and those COVs but I'm not sure what it is yet! Thanks for your help, it is much appreciated.

I lifted the engine and box out on Saturday, BLIMEY that's a heavy lump, my front end loader would only just lift it.

Change-Over Valves are 'either or' - that is they pass air from either of two circuits to whatever is downstream. The valve prevents back-feeding into the 'other' supply circuit.

Think of it as a shuttle-valve.

Are you, perhaps, confusing a Quick-Release Valve? This is normally in a circuit where 'quick-release' is desirable (such as a spring-brake parking supply - or rear airbrakes). When pressure is applied a diaphragm is held over the exhaust port so that the air supply can be passed downstream to the actuator - when the input pressure disappears the spring lifts the diaphragm off the exhaust port allowing the residual air to escape directly rather than having to return 'upstream' to the application valve exhaust port.