Flangeable valves hydraulic motors

Flange-mount valves are special valves that are mounted directly onto a hydraulic motor. Their main function is to control, block, or protect the hydraulic flow and pressure in a targeted way. They are essential for protecting hydraulic systems and components from damage caused by overpressure, for controlling the rotation direction or speed of motors, and for moving or holding loads in a controlled manner. By being mounted directly to the hydraulic motor, they enable a compact installation and reduce potential failure points in the system.

Single-acting shock valves protect hydraulic components from pressure spikes in only one flow direction. They limit the pressure in the specific flow path where they are installed. When the preset pressure is exceeded, the valve opens and diverts the excess pressure.

Double-acting shock valves, on the other hand, provide protection in both flow directions of a hydraulic system. They are especially important in applications with rapidly changing movement directions of hydraulic motors or cylinders, as they relieve pressure in both directions once a maximum limit is exceeded. This increases safety and component service life, especially in reversing operations.

• Overpressure protection: Shock valves and pressure relief valves prevent damage to components and systems caused by sudden pressure spikes.
• Load holding and controlled lowering: Overcenter valves and load-holding valves prevent uncontrolled lowering of loads by precisely regulating oil flow and locking in the event of pressure loss. Load-holding valves also ensure leak-free load retention.
• Leak prevention: Compact design and leak-proof valves reduce the risk of hydraulic fluid loss and system failures.
• Cavitation protection: Special features such as integrated check valves and make-up functions (in double-acting shock valves) prevent cavitation.
• Standards compliance: Many valves comply with common safety standards such as ISO or DIN.

• Mechanical engineering: general control and protection functions
• Agriculture: e.g., on front loaders and other agricultural machinery
• Construction: in cranes, excavators, and other construction machinery
• Industry: in conveyor systems, lifting equipment, and brake control
• Mobile machinery: for winches, snowplows, and similar equipment
• Mining: e.g., in shuttle cars

Installation is done via standardized flanges directly on the hydraulic motor or cylinder. It is recommended to position them close to the component being protected. Adjustment is usually performed using set screws or knobs on the valve, often with a factory setting of approx. 130 bar. For overcenter valves, the setting should be about 1.3 times the maximum expected load pressure. Operation should be with mineral oil-based hydraulic fluids and adjustments should only be made by trained personnel.

An overcenter valve with a brake release port is a load-holding valve that enables safe lowering of loads. The brake release port is used to hydraulically release a mechanical brake. The load can only be lowered when sufficient pilot pressure is applied to open the brake and release the valve. If pressure drops, the system remains locked, providing a double safety measure.

A shuttle valve operates on the OR principle: it routes fluid from the inlet with the higher pressure to the outlet and blocks the other inlet. Applications include:

• Load-sensing circuits
• Brake release on hydraulic motors
• Safety valve arrangements
• Mobile hydraulics
• Combining multiple check functions

Available valve types:

• Overcenter valves
• Shuttle valves for brake release
• Single-acting shock valves
• Double-acting shock valves

General technical data:

• Max. flow rate: 60 l/min to 200 l/min
• Adjustment range (pressure): Shock valves e.g. 30–100 bar, 50–210 bar, 80–300 bar; overcenter valves 60–280 bar
• Nominal pressure: Shuttle valves approx. 250 bar
• Port sizes: 2× G1/2" to 2× G1"
• Pilot ratio: Overcenter valves approx. 4.25:1