There are two independent braking systems both working on the rear wheels. A set of internal shoes operate on drums bolted to the rear wheels of the appliance, there is an equalising mechanism between these and the handbrake lever.

The foot brake operates a set of contracting shoes on a drum fitted to the gearbox output shaft on the front side and forming half of a universal joint on the rear side.

Handbrake

Brake Shoes

Brake Shoes

Adjustment

One should always ensure that the handbrake is well adjusted. Due to the relative twist between the rear axle and the chassis the adjustment must take account of this. As the axle twists under accelerating forces it winds on the brake, this needs to be avoided to prevent overheating and damaging the drums. Just over two notches on the ratchet is a good starting point for adjustment, the adjustment can then be checked while under heavy acceleration, there should still be free play in the lever, but it should be limited. The adjustment is done by the turnbuckle under the chassis rail on the offside of the appliance.

Removing the Shoes

  1. Remove one of the Rear Wheels.
  2. A pin locates the push rod to cam pivot bearing. Remove the nut.
  3. The pin needs to push out, but probably wants to stay in with all it’s might. I found replacing the nut a few turns to protect the thread, blow torching the surrounding metal and then hitting with a mash hammer does the trick. <This method might not be recommended>.
  4. Remove the two pivot pins from the bottom of the brake shoes.
  5. Remove Brake Shoes

Cleaning

The drums can be cleaned a little by means of jacking one of the rear corners and removing the handbrake. The wheel can then be rotated and thinners soaked rag held against the braking surface, repeat until the rag comes out clean.

To clean thoroughly however the rear wheels must first be removed. The drums can then be thoroughly degreased with the aid of a commercial degreaser (e.g. Jizer). The shoes can then be wiped clean with a thinners soaked rag. The shoes however also have a tendency to soak up a oil, this can be helped to a certain extent by heating the shoes slightly with a blow torch, this can help to sweat out some of the oil which can then be wiped off with thinners soaked rag. It is best not to use degreaser on the break shoes or they will squeak.

Relining the Brakes

The brakes require relining once the brake material has been worn down so the rivets that hold it in place are almost flush with the braking surface – the material needs replacing before the rivets start damaging the brake drum.

The shoes need removing (see above). The old material is then removed by removing the copper rivets. Note the two halves of the brake material are different sizes.

New material is required. The last two sets of linings were made of Saftek’s G.G.W Woven material. A piece 330mm x 254mm provides sufficient material. The last order was of 12mm thickness but given the filing required (see below), 10mm would be a better size to order.

The material then needs cutting into four sections. Note the material is reasonably flexible and will end up bent to the right shape as it attached to the brake shoe – prior to cutting into strips the piece is not particularly flexible.

The material is then clamped into place. The first hole should be drilled and then a bolt should be used to hold it in place whilst the second hole is marked, then drill the second hole. Repeat and drill no more than each of hole between remain bolting and clamping in place.

The holes will need counter boring. The counter bore is ‘usually’ found in the draw underneath the red vice.

If the material is too longer it will need cutting to length before riveting. Also at this stage any excess width needs taking off.

The lining is then riveted in place keeping the bolts in doing each line in turn. The rivets are 1/4″ diameter, and 1 and 1/4″ long flat head rivets.  100 rivets were bought prior to the relining of February 2012.

The shoes are then put back in place and the wheel should be put back on. It is entirely likely that the material is too thick for the drum to pass over it – the drum has a lip. In which case the material should be filled back so the wheel can go home. Tightening the locking nut with a spanner will allow the wheel to slide across the brake material if the material is only fractionally to thick – do this with caution to prevent damage to the thread or the brake shoes.

Foot Brake

There are a number of adjusters on the foot brake; we shall start with a general description of the operation of the shoes. The shoes are forced into contact with the drum by means of snail cams on an overhead shaft that is rotated when the foot brake is applied. The overhead shaft is also floating transversely so that the forces on the two pads are equalised. The shoes have their seating adjusted by two bolts on the lower side of the supporting assembly, the foot brake should be applied so that the pads are pressed against the drum, the seating adjuster bolts should be wound in until there is approximately 1/32″ between the shoes and bolts.

With the turnbuckle under the drivers foot board unwound adjustment of the snail cams should be done, they are adjusted by winding the adjuster nut on the overhead shaft to move them closer to together. This should be adjusted so that the shoes begin to apply around ¾” around the cam. The final adjustment should be made at the turnbuckle, the pedal needs around ¾” of free play to prevent the shoes rubbing as a result of chassis twist. Finally driving the appliance and checking the drum does not become warm should check the adjustment.