roller jamming

[PeteB]

A blowoff valve is a safety valve which opens when a certain hydraulic pressure is reached. This ensures that your hydraulic system isn't over-pressured and seals etc popped! The usual valve comprises of a ball bearing being pushed against a seal by a spring. This spring compresses under pressure allowing the oil to go through another circuit within the valve bank - straight back to tank. The pressure of the spring is set up so that moves at a certain pressure, this setting is adjustable to account for the spring tension getting weak with age and over a period of time, your blowoff setting can reduce from say 3000psi to 2000psi. Wind it back up and voila! Bloody good pull once more!