load senseing valve sticking ?

I am not exactly clear in what you are asking, this valve you are refering to, is it the load valve you are questioning or do you mean the wheel cylinder?

I feel, you need to approach this from the very basics in givening information also.

Now..., you say the wheels lock up every time you go out. Are the brake already locked on as you move or do they actually lock-on as you apply your brakes?

If they are already locked on before you move, it is more likely due to possibly oil contanmination into the drum. You will need to throughly clean out the shoes and drum surface with brake cleaner, re-set shoes and handbrake. Naturally, you will need to address the possible oil leak, by renewing your rear oil seals.

If the brakes lock on after you have moved, you will still need to strip the drum to investigate, the most probable cause will be a seized wheel cylinder, check on the shoes, that these are bonded on the shoe frame firmly and not seperating apart, in which case I would ask you to renew or re-shoe.

Please provide more feed back. If the brakes lock on only on application, then the answer is still strip down and investigate, you may have to turn your attentions to the load sensing valve, disconnecting the rod attached onto the rear axle will allow to over ride the valve's set load. If you imagine with some load in the vehicle the body will squat, in doing so the if still attached to the axle would effectively raise the valves lever, so if we raise the lever the load sensor adjusts to apply more brake pressure to the rear brakes, from this, if your brakes come on on an unladened vehicle, you will need to lower the lever, reducing the braking force to the valve. Should you have a successful outcome trying this, let me know and I will then send info on how properly set the valves height.

With assistance, get some one to apply your brakes and check your rubber rear brake hose for any swelling or balooning, should you see any swelling, replace the brake hose. Should only one wheel lock, then it could mean the rubber hose on that side of the vehicle is internally deterioating that the rubber on inside wall behaves as an one way valve.

Investigate the shoes and let's take it from there.

Cheers,