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Hydraulic power units

Hydraulic clamping power units or clamping pumps are especially designed for hydraulic clamping.

Hydraulic power units of compact design, ready for connection Suitable for the control of all of the listed clamping elements Individual solutions are possible by using the unique modular system On request also with turnkey on-site installation.

flow rate: 0.82 ... 12 l/min
operating pressure: 160 ... 500 bar
oil volume of the reservoir: 5 ... 63 l
motor rating: 0.75 ... 3.0 kW
motor voltage: 400 VAC 50 Hz

Series Data sheet Technical data
WZ 8.800 Hydraulic clamping pump


manually operated

max. operating pressure 100, 200 and 500 bar

oil volume: 300/970 cm3
usable oil volume: 150/750 cm3
displacement per stroke: 2 .. 8 cm3
pump supplied is filled with oil

WZ 7.1600 Hydraulic power unit


flow rate 0.82/2,1/3.5 l/min

flow rate: 0.82 .. 3.51 l/min
Operating pressure: 160 .. 500 bar
reservoir volume: approx. 5 l
usable oil volume approx. 3.2 l
continuous duty: up to 120 s
motor rating: 0.75 .. 1.1 kW
motor voltage: 400 VAC 50 Hz

WZ 7.1800 Power Units in Modular Design


Operating pressure 30 to 500 bar

flow rate 0.9 to 12 l/min

reservoir sizes 11 l, 27 l, 40 l, 63 l

The power units of this series consist of individual modules that are selected depending on the application and are assembled on the basis of a type code to a power unit ready for use.
- power unit (reservoir, pump, motor)
- connecting block basic functions
- valve block with up to 4 control circuits
- electronics

figure 1: Hydraulic power unit series D 8.0115

figure 2: Pressure-time diagram for single-acting clamping cylinders

figure 7: Power Units in Modular Design


Hydraulic power units are supplied as compact units ready for connection:
Complete with motor, pump, reservoir, connector block, pressure gauge, pressure switch, solenoid valves and, on request, electrical control systems. Upright mounting position, pump with three or five radial pistons, direction of rotation optional.
These power units operate in energy-saving intermittent mode with automatic pressure monitoring, i.e. when the pressure set at the pressure switch is reached, the motor switches off automatically. If pressure drops 10 % below the set value the pressure switch causes the motor to start again.
Using the version with machine safety, the machine is stopped, if the clamping pressure falls by more than 15 %.

Hydraulic power units series D 8.0115 (figure 1)
These power units are especially suitable for the operation of small to medium-sized hydraulic clamping fixtures.
Maximally 2 clamping circuits for single or double-acting cylinders are available, that can be controlled independently of each other. Thereby also "shuttle machining" is possible, i.e. that during machining of the workpiece in one fixture, workpiece change on the second fixture can be made.

A special feature is the mounting of pump and electric motor in the reservoir. Thus hydraulic and electric control can be arranged in a space-saving way and easily accessible on the reservoir cover. The modular design enables a multitude of control variants.
The radial piston pump is available with 3 different flow rates and operating pressures. To allow an energy-saving intermittent cycling only leakage-free poppet valves are used.

Energy-saving intermittent cycling
The electric motor is only running, as long as hydraulic oil is really required, that means to
• extend and retract the clamping cylinder
• build up the operating pressure

Pressure-time diagram for single-acting clamping cylinders (see figure 2)

In this example of a hydraulic clamping fixture the running time of the electric motor corresponds to the clamping time, which is only a few seconds.
In standby mode the power consumption is relatively low. The conditions are leakage-free clamping elements, valves and accessories.
The pressure control is made by an electronic pressure switch, that switches on the electric motor for a short time in case of a pressure drop.

Power Units in Modular Design 7.1800 (figure 7)
Operating pressure 30 to 500 bar, flow rate 0.9 to 12 l/min
reservoir sizes 11 l, 27 l, 40 l, 63 l

For the operation of hydraulic clamping fixtures and other handling and clamping systems on machine tools.

The power units of this series consist of individual modules that are selected depending on the application and are assembled on the basis of a type code to a power unit ready for use.

• Power unit (reservoir, pump, motor)
• Connecting block basic functions
• Valve block with up to 4 control circuits
• Electronics

• for single and double acting cylinders
• continuously adjustable operating pressure
• expandable to up to 8 pressure circuits
• constant flow rate
• wide range of valves
• wide range of hydraulic functions
• energy-saving mode S3 (intermittent mode) or S6 (unpressurised cycle)
• supplied ready for Connection

Equipment - Standard
• connecting block with pressure relief valve
• pressure filter 10 μm
• oil level gauge
• oil temperature gauge
• design without piping

Equipment - Options
• electronic system pressure Switch with simplified pressure adjustment by teach-in function
• pressure switch for machine tool interlock
mechanically or electronically
• electrical oil level control
• electrical temperature control
• return filter
• electrical filter control
• electric control
• terminal box
• foot switch or manual switch
• key-operated Switch

Further Description
data sheet WZ7.1800


Accessories for the power units series 8.0115

Machine safety
As an option, every clamping circuit is checked by an additional pressure switch, which has to be electrically connected directly to the control of the processing machine.
1. Clamping pressure available Workpiece or die cannot be clamped
2. Clamping pressure dropped below 80 %: Stop machining immediately
(The switching point must be set to approx. 80% of the adjusted clamping pressure.)

Handle "B"
With the handle, the power unit can be easily transported by two persons to different places of installation.

Electronic pressure switch for machine safety "E"
(instead of the mechanical pressure switch)
The lower switching point (80 % of the clamping pressure) of electronic pressure switches is firmly programmed and can be stored in teach mode for every desired clamping pressure by pressing a button.

Oil level and temperature control "T"
The oil level and temperature control is installed in the reservoir cover and electrically connected to the control box. In case of an error message, the control LED below the main switch is lit.