Load Holding Cartridge Valves
Sun Hydraulics Inc, globally recognised manufacturers of Load Holding Valves which exceed the expectations of Original Equipment Manufacturers (OEM) and designers worldwide. Unsurpassed quality, high performance and durability at competitive prices. Sun Load Holding are used to control the movement of actuators (linear-hydraulic cylinders or rotary- hydraulic motors). Load Holding Valves are also known as Counterbalance Valves or Pilot to Open Check valves.
Cartridge Valves offer advantages to designers and owners of machines. A cartridge can be installed in a custom manifold with other valves to form a compact arrangement to control different functions of a machine. Cartridges can be installed in such a way as to eliminate multiple connections such as hoses and fittings all of which are liable to become loose and leak, hoses are expensive and bulky: Load Holding Valves can be sized to meet the exact requirements of that part of a circuit, a large Relief Valve, smaller Pressure Reducing Valve, Sequence Valves as required with Load Holding Valves to control actuator movement. Maintenance is a matter of testing, identifying the failed valve and removing only that cartridge without interfering with hose and fittings- quick and clean. A cartridge valve is a self contained valve with no loose parts, it is simple to remove defective parts and replace them with basic tools. Line Bodies are available to allow one or a couple of cartridge valves to be installed in a system. Common port options in Australia are BSPP or UNO, these are parallel threads where the sealing is done by elastomeric seals and the cartridges are retained by threads- the taper thread forms are not recommended for aluminium bodies, premature cracking is likely. Sealing methods like Teflon tape can lead to contamination of the hydraulic system and valve failure/ sticking etc.
Sun Load Holding Valves are available for flow rates from a few litres or so to 480 litres/minute in a single cartridge. There are 2 basic types of Load Holding Valve, Pilot to Open Check Valves and Counterbalance valves. A pilot to Open Check Valve is ideal for “locking” an actuator in one position, say extended or retracted, they are suited to systems where there is no significant suspended load- in the event there is such a situation a Pilot to Open Check valve might judder or pulse from mild to destructively heavy hammering as the valve switches from closed to open to closed. For circuit where a progressive opening and smooth movement is required a Sun Counterbalance is recommended, these might be internally drained, atmoshperically vented, internally vented, various pressure ratios and unrestrictive, somewhat or even Ultra Restrictive. A feature of Sun Counter Balance Valves is the fact they act as a relief valve in the event of overload allowing oil to escape to tank preventing damaging over pressure events.For design assistance and Load Control Valves contact Corridor Connections. Typically, Load Holding Valves are controlled with “Motor” spools in directional control valves, this allows the relieved flow to return to tank in an overload condition and prevents pressure build up in the “pilot” port opening the Load Holding Valve and movement of the controlled actuator.