Counterbalance Valves vs. Brake Valves

Counter balance valve

Brake valve:

Hi Mark

What is the main physical difference between the two spools

I'm not quite sure if my answer to this is what you are looking for, however, the two types of valves are completely different and perform different functions.

A brake valve is a modulating valve and (hydraulically) allows flow in both directions (of which, one direction is 'power assist').

A counterbalance valve is a load hold valve with free flow in one direction and controlled flow (subject to pilot through variable relief) in the opposite direction.

Both valves have many different variants!

A brake valve will supply oil to a brake.

A counter is limiting flow so the oil is applied to the counter, thus is subject to system changes like cavitation that may render the valve useless in certain situations if used as a brake valve. Not Safe.

The function of brake valve is same as counterbalance valve. The key difference is the pressure drop across the counter balance valve is convertted in to heat. Due to this a large amount of hydraulic power wasted and the brake valve is used to avoid this disadvantage.