berg-ohsr

Hydraulic Cylinder - OHSR

Hydraulic cylinder with open center

The rotating hydraulic cylinders type OHSR actuate open centre chucks and are suitable for bar stock and individually chucked parts.

Design features
The rotating hydraulic cylinders type OHSR actuate open centre chucks and are suitable for bar stock and individually chucked parts. They consist of the rotating cylinder equipped with unlockable non-return valves, a hydraulic rotary transmission leadthrough which moves axially with the piston stroke, a coolant collector and a stroke control device. This construction permits a compact design. Accidental energization of the inductive proximity switches by chips is excluded as they are positioned outside the coolant collector.
A threaded spindle facilitates the setting of the proximity switches.

The sealing gap of the rotary transmission leadthrough guided contactfree by roller bearings is designed to ensure that the loss value dependent on the height and length of the gap and viscosity of the fluid remains as low as is physically possible at maximum pressure and maximum rotational speed.

The patented BERG valve system maintains the clamping pressure in the cylinder in the event of a sudden pressure drop. In clamping position it allows infinitely variable reduction of the clamping pressure. Pressure peaks from the hydraulics or as a result of clamping pressure increases due to overheating which can lead to constant overstressing of the clamping means, are rendered ineffective.

A system of labyrinthine chambers between the coolant cover and the rotary transmission leadthrough housing ensures reliable and permanent separation of the oil and coolant circuit. The outlet opening of the coolant collector is very generously dimensioned to prevent accumulation of very large chips.

The delivery scope includes a fastening ring which, in conjunction with a securing ring, allows axial fixing of bar guide tubes.

BERG valve system
The valve system is effective in both directions of actuation (push and pull). The opening pressure is 4 bar. Before using self-regulating positivedisplacement pumps, check whether the delivered flow is sufficient to ensure an adequate piston speed at minimum pressure.
To guarantee the function do not install any non-return valves downstream of the pump.

Filter regulations
Ensure that a pressure filter is fitted between the pump and the solenoid valve (filter fineness 0.010 mm absolute, filtering coefficient 75).

Oil regulations
HLP 32 according to DIN 51524 (32 Centistokes bei 40 °C): The temperature of the backflowing oil should not exceed 70 °C due to the risk of ageing; otherwise, provide a larger oil reservoir or an oil cooler.