Spring assisted sealing elements
for requirements that cannot be addressed using conventional elastomers. With fluoroplastics they can withstand temperatures from –200°C to +250°C and are resistant to aggressive media.
Adjustable displacement pump
Variable pump on which the geometric displacement can be set (limited) to a specific flow rate . This setting is made, e.g., by means of a stop screw that fixes the pivoting of the cylinder drum to a specific
Digital
variable to be represented by a code . If the variable to be represented is analogue, the code assignment can only be undertaken after defining the levels ( quantising ) ( analogue/digital converter ).
Types of mounting of cylinders
cylinders a differentiation is made between four basic forms (Figure B 4) : Flange mounting : The flange can be attached to the head (item a) or to the base (b). In a, position B, the fastening screws must absorb [...] in all planes (h). The centre of gravity is always at the end of the cylinder. Trunnion mounting : Can be attached at any point along the length of the cylinder (i, k). A common design is pivoting at the
Operating viscosity
Information on the operating viscosity characterises the viscosity range in which the entire system can operate. A differentiation is made between three 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 cause cavitation to occur in the pump. Minimum operating
Measuring device
measured signal and output a measured value to represent a measured variable (Figure M 19). Between these can be found transfer elements such as measuring amplifiers , and measuring converters . Since these devices [...] position in the feedback section will, however, have a real impact on the controlled variable , which can never therefore be more accurate than its measuring device!
Speed characteristic of hydraulic motors
motors at Q 1max and on variable displacement motors at the V 2min at which the internal friction can still just be overcome. The lowest rotation speed is reached if Q 1 is just greater than the leakage [...] 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 via the pivoting angle.
Differential pressure
Measured variable for the pressure difference between p 1 and p 2 . The differential pressure can be positive or negative, depending on whether p 1 is greater than p 2 or smaller than p 2 (Figure D 23)
Efficiency of pipe
and form-related losses — neither of which are related to pressure. As such, the efficiency of pipe can be expressed as follows: This means the higher the efficiency of pipe, the higher the operating pressure
Performance map
variables, with one or more variable parameters being used as parameters. This kind of performance map can provide a complete overview of the behaviour of the respective device in all operating states recorded