Hydromechanical efficiency
These give a total loss torque M V With hydraulic pumps, this loss torque must also be counted in addition to the theoretical torque (Figure H 11) : which in turn gives With hydraulic motors by contrast, the [...] the usable torque is reduced by the loss torque (Figure H 12) : which gives With hydraulic cylinders, most friction is caused by the seal (F Re); which in this case gives Total efficiency, power losses
Plug-in valve
Valve on which the housing is in the form of a cartridge and with port openings that are aligned with the ports in the installation space (e.g. 2-way plug-in valve).
Round sealing rings
Collective term for seals with a round or almost round cross section. The most important is the O-ring. Another is the Quad-ring along with others within this group ( Figure R 40 ).
Pressure independent flow control
throttle function ( throttle valve , continuous directional valve) with a (control throttle) that provides a load pressure independent flow rate with a magnitude defined by the throttle position.
Overlap in valves
In general : For control elements with a piston design, this states the seal length between the allocated control edges ( Figure U 1 ). in rest position, together with the size of the gap, it determines [...] of the characteristic curve . For directional valves the length of the control piston in comparison with the ring nuts results in three variations: Positive overlap : The piston is longer than the ring nut [...] movement ( Figure U 1 b ). Zero overlap (zero cut) : The control edges of the piston and ring nut meet with a high degree of accuracy. In this position, there is no flow rate (apart from leaked oil), but it
Analogue control
signals in the signal processing and that also uses with progressive function elements. An example is the analogue position control shown in (Figure A 17) with absolute measuring procedure (inductive position
Operating viscosity
key figures: Maximum start viscosity : Characterises the still just permissible viscosity limit and with it the lowest temperature at which the system can still just be operated. A higher viscosity will [...] : Is defined by the reduction in the lubrication properties and the increase in the leakage losses with excessively thin oil. It marks the upper temperature of the oil that is just permissible. Maximum [...] devices in the system (e.g. valves) as well as by the time it takes air bubbles to rise. Together with the min. operating viscosity, the oil temperature range in which the system is fully functional is
Speed characteristic of hydraulic motors
axial piston machines with 7 pistons approx. 28 rev/min. and with 9 pistons approx. 16 rev/min.). At lower rotation speeds the relative delivery fluctuation can be corrected with the aid of a control algorithm
Ultrasonic position measurement
lengths of up to 5 m, and US measurement with magnetostrictive wave guide ( Figure U 13 ). Here current pulses flow to the wave guide, the magnetic field of which meets with a permanent solenoid on the moved [...] In position measurement with ultrasound (US), a US signal is issued, which is reflected by the moving body. The duration of the system measured in this way is proportional to the distance travelled. A
Shut-off unit
Unlockable check valve with twin design. The shut-off unit is arranged to compensate for leaks from directional valves with a piston structure between the consumer (e.g. cylinder ) and the directional