With the increasing automation of mobile work machines (construction machines, agricultural machines, municipal machines), there is an increasing requirement for electronically operating hydraulic valves with proportional behaviour. The oil flow has to be regulated in order to fine-tune speed and power of a hydraulic cylinder or engine.
At the same time, the machines’ sizes and subsequent flow quantity and performance density increase. The former direct control in which an electronical solenoid operated the valve’s piston directly ceased to be sufficient concerning cost-efficiency since the solenoids would become too expensive, based on the pressure and flow forces here.
Therefore, the so-called pilot control established itself here, in addition to the above-mentioned direct control: a small valve controls the pressure onto the valve piston which, in turn, controls the oil flow within the machine. In this connection, the classic separation of solenoid and valve is dismissed – MSM provides a complete small valve, the pilot control valve as actuator for the main valve.
For many years, MSM has had these pilot control valves, the so-called proportional pressure reducing valves, size (=diameter) 32 mm, in its programme. In order to meet market needs concerning the optimization of space required and costs, MSM has added a new valve model range, size 30mm, and extensive optimizations for manufacture.
Since customer-specific constructions are standard in the field of hydraulics, the constructional structure is largely modular. Currently, provisions are made for AMP and German plugs as electrical connectors, basically, other plug variants are technically possible. Protection class IP69K is sufficient concerning the requirements in mobile machines. The filter at the pump connection which can be seen on the picture is available as an option. The supply voltages available in the applications are offered in nominal voltages of 12 V and 24 V.
The control pressure of the valve is approximately 28.5 bar, in case of pressure drop by 10 bar, flows of up to 4 l/min are achieved. 50 bar input pressure and maximal 30 bar tank pressure are admissible.
In order to operate the valve manually in case of service or disturbance, there are also solutions for an axial manual override.
The valves win over by small hysteresis as well as short positioning times.
The modular structure allows for versions without valve part as switching or proportional solenoid. Furthermore, other valve functions, such as switching valves, are feasible.
Further technical details are available here.