Bill_M
Bronze Member
CT,
The cushion valve or a cross over relief valve protects the components by letting fluid go from on end of the cylinder to the other at a preset level with out passing through your regular service valve.
Example, No cushion valve in system. You have a grader blade on the three point hitch and catch the left end on a tree stump. One of several things can now happen. Engine stalls, tires spin, stump breaks, blade or hitch parts break or bend, hydraulic lines blow because the pressure that has built up as the blade pushes against the cylinder is more than they are rated for.
With cushion valve blade hits stump, pressure rises in the cylinder and line against the valve relief setting. When the setting is reached it opens and allows the oil to cross over into the other end of the cylinder until the pressure is below the setting. This will result in a movement of the cylinder, but protects the components from excessive damage.
Most snow plow angle circuits use one of these.
Both the A and B hoses on the service valve connect to two ports on the cushion valve. Both cylinder hoses connect to two ports on the cushion valve, basically it forms a "H" between the two hoses with the cross bar "-" being two relief valves that let fluid flow into the other hose.
The cushion valve or a cross over relief valve protects the components by letting fluid go from on end of the cylinder to the other at a preset level with out passing through your regular service valve.
Example, No cushion valve in system. You have a grader blade on the three point hitch and catch the left end on a tree stump. One of several things can now happen. Engine stalls, tires spin, stump breaks, blade or hitch parts break or bend, hydraulic lines blow because the pressure that has built up as the blade pushes against the cylinder is more than they are rated for.
With cushion valve blade hits stump, pressure rises in the cylinder and line against the valve relief setting. When the setting is reached it opens and allows the oil to cross over into the other end of the cylinder until the pressure is below the setting. This will result in a movement of the cylinder, but protects the components from excessive damage.
Most snow plow angle circuits use one of these.
Both the A and B hoses on the service valve connect to two ports on the cushion valve. Both cylinder hoses connect to two ports on the cushion valve, basically it forms a "H" between the two hoses with the cross bar "-" being two relief valves that let fluid flow into the other hose.