Priority (Swing) Motors Data and Specifications

Transcription

1 s Data and Specifications Specifications HMF 55 HMF 75 HMF 105 cm 3/rev in 3/rev Pressure Ratings Nominal 5000 PSIG Maximum 6090 PSIG Peak 7250 PSIG Operating Speed Maximum Oerating Speed Mininum Contact Factory Envelope Size L W H Weight

2 Control Spool (1) Shown in Full Actuation Operation Circuit Diagram MA MB L U 4 4 A B X Y T P EXPLANATIONS P Pump T Tank signal L, U Drain (filling, vent) ports connection enabling case to be filled with oil X, Y Pilot pressure ports MA, MB Gauge ports, swing pressure Pilot pressure in X Pilot pressure in Y : clockwise rotation : counter-clockwise rotation High pressure (pump) Low pressure (return) pressure (service signal) Control pressure Reservoir (Case pressure) 2

3 T to the reservoir P from the pump Compensator Main spool Return oil check valve TC-Valve max. TC-pressure T A P B T Pilot control valve X Y Relief and make up valves Feed valves L HMF P Piping installation: Multiple disk brake P = T = Pressure supply from hydraulic pump Return line to reservoir Planetary gear = Load sense signal X = Pilot port (relief to reservoir) Y = Pilot port (pressurized) L = Drain (filling, vent) port Pinion 3

4 Diagram Torque Control Secondary setting 200 Limitation by pilot pressure 80 working pressure swing [bar] Minimum setting value swing speed [%] pilot pressure [bar] TC-characteristic [bar] Secondary valve [bar] Speed [%] 4

5 Functional Description The basic unit is a fixed displacement motor of the HMF- 02 P type. It is an axial piston motor of swash plate design for open loop, designed for use as swing motor and equipped with all functions for optimum swing drive. The following functions are integrated in the valve plate housing of the motor: a. Directional control valve b. Priority for swing drive c. Torque Control (TC -valve) d. Pressure relief and make up valves VD e. Feed valves Technical Description a. Directional Control Valve The control spool (1) of the directional control valve (please refer to circuit diagram) is used for controlling the speed of the motor. This control spool is centered in neutral position by two springs and pump pressure is fed to the motor via port P. Depending on the requested direction of swing, pressure is built up within the respective spring chamber (X or Y) by means of a pilot controller (joystick). The control spool (1) is moved according to the preselected control pressure and connects oil flow from P to A (B) and B (A) to T. The opened cross-section has an orifice function behind which -pressure is taken off and is reported to the pump control. Depending on the pilot pressure, the oil quantity (swing speed) is adjusted. The maximum spool stroke and consequently the maximum flow, can be limited by means of an adjusting screw. The throttle check valves (8) dampen the control spool (1) in both directions. b. Priority Swing Drive Function Inside channel P is connected in series to the control spool (1), there is an up stream compensator (2). Together with the check valve (7), priority for the swing drive is realized. 5

6 Functional Description c. Torque Control (TC - valve) The TC - valve (3) defines the accelerating pressure. By means of the pilot controller, the operator selects not only the requested oil quantity but also the variable accelerating pressure. Thus, waste of energy by oil passing the high pressure relief valves (4) (secondary valves) is avoided. The maximum accelerating pressure is defined at the TC pressure relief valve (5) (please refer to diagram page 4, example). It should be below the setting of the high pressure relief valves (4). d. High pressure relief and make up valves with relief pressure step up VD These relief valves are variable and are set at a basic value (see diagram, example). With a pilot pressure > 5 bar at port X or Y, the set pressure of the valve is raised from basic to top value. As control pressure, the remote control pressure of the directional control valve is used. During the acceleration phase, the setting of the respective valve is changed by pilot pressure to the maximum setting according to a characteristic curve. If smooth coasting is desired by the shovel operator, the pilot valve must be held in zero position. The upper carriage will then run against the lower setting of the secondary valves (minimum setting 50 bar). If the upper carriage is to stop harshly, the driver has to overcenter and switch the corresponding secondary valve to its maximum value. Now the upper carriage will brake against the maximum pressure. According to the pilot pressure chosen by the operator, the braking pressure can be tuned along a curve between the maximum and minimum value, both mechanically adjustable from the outside (see corresponding Service Info). The correlation between pilot pressure and TC curve can also be adjusted from outside. The discharge side of the pressure relief valves (4) is always connected to the pressurized return line to reservoir so that the make up valves can fulfil their function. e. Feed Valves In order to avoid cavitation, direct feeding of the swing system via the feed valves (6), which are connected to the return line to reservoir, is possible. The check valve (9) (in P-line) makes sure that this function is maintained even during countering and at lowest system pressure. 6

7 Basic Design of Rotating Group EXPLANATIONS 4 High pressure relief and make up valves with relief pressure step up VD Check valve ( passage) 10 Check valve (return oil to reservoir) 12 Cylinder barrel 13 Valve plate housing 14 Shaft seal 15 Shaft 16 Working piston 17 Valve plate 7