Bedford TK rear park brake setup.
 

Hi all,

I have a TK Bedford, model I believe is KC, 16inch wheel model and year around mid 1970. It has an air actuated park brake, the pressure pot is mounted on the diff. The pressure pot has an internal piston / spring and a rod to then actuate through levers to long 2 rods. One of these long rods goes to the LH rear brake bisector, and the other to the RH brake bisector. Both these rods and the pressure pot rod have adhjusting threads on them.

Can someone please tell me how to set up this park brake system, all I know is that it has to be done with the air on, so the spring is compressed in the pot.The spring is what puts the brakes on when there is no air pressure.

Thanks for your help :)

Christine

P.S(I am a mechanic all you guys, so can do this if I know the procedure / settings)

I'm not sure of this set up Christine, but I would advise you to beware of having hands and fingers on the short rod that comes out of the actuator when it is applied. If it was I think it is, then it applies the brakes by pulling the linkage and not pushing it. This means that the spring is in the front of the actuator pushing the piston back and not behind the piston pushing it forward. Unfortunately if it is this set up unlike most spring brakes there is no way that the brake can be wound off by mechanical means and the way I was warned about was '' get your hands away from that or you will end up wearing it like a glove '' .

I would imagine (using logic, not experience) that you first adjust the wheelbrakes so that they are as close to the drums as possible and don't rub, then, with the air system charged adjust the parking brake linkages until there is no slack but they are not causing the brakes to drag.

Hi.
I have no vintage truck, or particular knowledge of them, but I do have a set of five Bedford Truck and Coach Service Training Manuals, which a relative has asked me to sell on eBay. I have not listed them yet. In the front of the "Brakes" manual, it says "This manual provides the experienced serviceman with information on the special features of the brakes used on 1973 Bedford trucks & coaches, except Series M4 x 4 trucks,....."
Sections 153 and 153a deal with parking brake linkage and adjustment; is that what you are looking for?
Unfortunately, I am also not a computer whizz, so I cannot find out how to attach a photo. If you would like me to send it to an e-address, I will willingly do so.

The easiest method (unless you have a scanner) is to take a digital photograph then upload it to a site such as Photobucket.com then copy the URL (that begins IMG) and paste it into your text message here.

Alternatively, just copy (word for word) the text (typing it into here). It's slow but words is words and easily read wherever.

1973 bedford - parking brake setup
 

I hope that the two photo's of the pages from my manual transmit OK, and that they are of help.


Attachment 276

Attachment 277

Parking brake setup - 1973 Bedford.
 

Omitted to send a further 3 photo's. Here they are.Attachment 278

Attachment 279

Attachment 280

I am sure that you can sort out the order they should be in!

When trucking i recommend having a contact with a mobile truck mechanics Carindale that is very helpful specially in problems on the road.

Can I ask a question. I have 74 TK cab Bedford
Currently have no air so does this mean my park brake is on or off
I thought no air meant brakes are off

My logic tells me; If you were to park on a hill, the parking brake should stay on, even when the air pressure leaks away to nothing! There is no mechanical lock on the parking brake. A spring apples the parking brake and the air overcomes the spring when the parking brake is released. My 76 TK has the same parking brake set up and the rods push from the central mechanism and into the cylinder on the drums when the air pressure is applied.
My old manual does not cover this modern system so I would love to know how this works, as I’m trying to remove the drums but it’s all rust and no give.

TK Bedford park brake
 

Jim.
Thank you I had a mate push and hold the broken air line in. You can see the piston slowly move to release the park brake just need now to get fitting for the air line
Lifted the back end up with a back hoe and wheels now spinning
You will need air pressure to get the hub off or adjust the brake shoes wind them off
Then use a puller to slowly work the drum off.

Small detail but they are pull rods.

Push & pull
 

Got my parking brake mechanism on the bench this morning, when I apply air pressure the rods push outwards towards the hubs. Or they try to, needs some TLC. Having said that, I’ve only driven it 50 meters and the brakes were sticking. Is there 2 types? I’ve put a photo of mine. I got the hub off by disconnecting the park brake rods and rigging up a puller. The adjuster just span in the crown shaped gear, but it came off any way.

Looks pretty similar to mine but I think some TKs don't have air at all - vacuum brakes.

NB: rods are missing here

I have just realised that you the author of the blue tk restoration blog which I have been reading over the past few months and using as a source of info when I get stuck. Best bit of info on the internet about TKs that I have come across. (I’m just buttering you up before I ask a load of technical questions!).

No problem, just ask away; I have a lot of pictures!

Truck is standing in the yard at the moment and I haven't driven it in a while. We had some sort of virus going round in the autumn and were not allowed to travel for a while.

This group has some very knowledgeable people on it

https://www.facebook.com/groups/1198517853610561

I’ve got one rear slave cylinder and shoe expander mechanism off and it appears obvious that the rollers need to be pulled up the wedges in order to expand the shoes. I have triple checked my set up and it pushes the rods when pressured. My set up must have been wrong before it seized up. I’m thinking what could be wrong how to correct it. Wedges are upside down? The rods go to the wrong side? or my pressure pot pushes when it should pull? Looking at your pressure pot (assuming it is not pressured) and the leaver positions, it looks like it will pull, is that so? Am I missing something simple or just confused.
I will have a fresh look at it next week, beach and booze this weekend.

It sounds like it's working fine. When the handbrake is on, there is no air pressure and the spring brake pulls the rods, which pulls the wedge which expands the shoes applying the brakes. When the handbrake is off, the air pressure compresses the spring brake, which pushes the rods which pushes the wedge which releases the brakes.

For the handbrake the spring applies the brake and the air pressure takes the brake off. It's a fail-safe thing - when there is no air pressure the brakes come on.

Back on it today. Of course, that’s so simple but I just couldn’t see it. As my dad would say, ”you can’t see the wood for the trees”. I had wrongly assumed pressure = brakes on! I can just focus on the rust now. Lots of cleaning and painting in progress. Thanks.

Looking good.

On the subject of spring brakes and dismantling them - don't.

(In case you didn't already know that)

When I unseized the front slave cylinders, they were well stuck. I pushed them out with grease by filling the brake pipe hole and winding a bolt in to force it in to the cylinder. It took a long time but was controlled. Did one of the back ones today and I had the air line handy, the piston hit the roof like a rocket. I’ll leave the pressure pot be. It appears to work ok.