These hydraulic-over-air relay valves are designed to convert hydraulic modulated input pressure to a proportional output air pressure.

Then, if traction is lost at one or more of the tires, a valve on a central hydraulic controller relieves some pressure to the slipping wheel (s) to regain traction.

The Fluid Power Safety Institute examined a case where a worker was injected with high pressure fluid. Based on discussions with maintenance personnel and machine inspections, ...