Flow direction is reversed by tilting the swash plate to the opposite side of the neutral or zero displacement position.

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2 General Description Axial piston variable displacement pumps, Series 20, are of swash plates construction with variable flow capability suitable for hydrostatic transmission with closed loop circuit. The Flow rate is proportional to the pump s driven speed and displacement, which, in turn, is determined by the swash plate angle. The latter infinitely adjustable between zero and maximum displacement. Flow direction is reversed by tilting the swash plate to the opposite side of the neutral or zero displacement position. Figure 1: Features Axial piston variable displacement pumps, Series 20, are well-engineered and easy to handle. The full-length shaft with a high efficient tapered roller bearing arrangement offers a high loading capacity for external radial forces. Additional pumps can be built on. The hydro-mechanical servo displacement control maintains the selected swash plate position and hence pump displacement.

3 Upon release of the control handle, the swash plate automatically returns to the null position and the flow become zero. High case pressures can be archived without leakage even at the lowest temperature by using suitable shaft seals. The servo valve arrangement offers the facility to incorporate function regulators and remote control system. Axial piston units are designed for easy servicing, complete dismantling and reassembly can be carried out standard hand tools, and all components or sub-assemblies are replaceable. Figure 2: Figure 2 shows schematically the function of hydraulics transmission using an axial piston variable displacement pump and a fixed displacement motor.

4 Technical data Table 1: Dimension cm3 33,3 51,6 69,8 89,0 118,7 165,8 2,3 333,7 dm3min-1 119, , , ,5 1 8, , ,59 557,2 8 Displacement per revolution of the charge pump cm3 12,3 12,3 18,03 18,03 18,8 32,8 32,8 65,5 Max. pressure MPa 35 Nominal pressure MPa Max. pressure of control MPa 3,5 Charge pressure MPa 0,8 2,0 Max. pressure in case MPa Maximum speed + min -1 Minimum speed min -1 Nominal speed min mm2s Max. displacement per revolution of the variable displacement pump Max. flow Kinematic viscosity range of working fluid - starting - operating - optimum 0, continuous Operating temperature Max. temperature of working fluid in tank o C - 40 to + 50 C 80 µm 10 Direction of shaft rotation Weight mineral oil o Maximum swash plate angle Kind of working fluid Purity of working fluid 90 0,5 intermittent clockwise or counter clockwise ± 18 o kg o for higher speed contact our Application department Figure 3: External drain fluid loss for frame s Determination of nominal pump

5 CURVES DEPENDENCES OF EFFICIENCY, FLOW AND OUTPUT ON THE SPEED (for operating condition of 18o swash plate angle) Figure 4 For frame 20 For frame 22 For frame 23 ŋv = Volumetric efficiency ŋt = Total efficiency

6 Servo Displacement Control (Linear response) Regular by control handle on the servo valve, the swash plate can be infinitely varied in both direction with the help of the servo system. The pump displacement resulting from any control handle position can be established using figures (5a 5c). The angle of the control handle for stroke initiation and for the final position of the stroke can vary from unit to unit within the range of the tolerance band. (Figures 5a 5c) Figure 5 Figure 5a: frame 20 Figure 5b: frame 22 Figure 5c: frame 23

7 Reversing Time Time for the directional of the flow from Q max across 0 to Q max depending on the of the control orifice fitted in the supply port to the servo valve (Figure 7). The values given assume movement of the control handle directly from one end position to the other. Adjustment time of handle: Operating pressure: Speed: Viscosity: < minimum reversing time MPa 1450 min-1 35 mm2 / s Schematic diagram of servo valve with recesses for alternative orifice position Servo valve counter bored orifices insert The reversing time in one flow direction can be extended by inserting an orifice in one of the pilot ports only. Table 2: diameter of orifice (mm) 0,91 1,36 1,6 0,91 1,36 1,6 0,91 1,36 1,6 reversing time (s) 3,78 2,72 2,16 1,6 1,14 0,6 6,06 4,2 3,42 2,3 1,74 0,96 6,24 4,8 3,54 2,7 1,8 1,02 24 diameter of orifice (mm) 1,60 1,60 1,60 1,60 reversing time (s) 10,20 5,82 2,88 1,68 11,58 5,92 3,12 1,86 29,70 16,20 7,50 3,78 30,90 15,72 7,80 5,64

8 Dimensions Table 3. Dimensions (mm) A A1 B B1 B2 B , , , , , ,5 317, ,4 165,1 165,1 177, H1 H2 H3 L L1 81, ,2 106, ,7 158, , T U 19 9,4+0,2 D4 56 H 19-0, 94,7 108,7 112,7 1, ,7 170,3 187,2 55, ,3 77,8 87, ,3 68, V3 X Y Z ,35 9,5 12, ,3 17,5 3 6,35 9,5 12, ,3 17,5 k l l1 α m n 48 12,5 min20 52,4,2 12, , ,4 36,5 h2 6, , SAE flange, 3000 psi 4 threads, 3/8 UNC-2B, 18 deep 7/8-14 UNF-2B 15/16 12 UN-2B SEA flange, 11/2 4 threads, 6000 psi, 5/8-11 UNC-2B, 35 deep W 1 7/8-12 UNF-2B SAE straight threads O ring boss d1 d 3/8-16 UNC-2B 5/8-11 UNC-2B 45O P1,2 drain, , ,4 317,4 S1 115,9 128,6 128,6 139,8 152,3 165,1 167,4 190,5 51, , , ,4 95,3 G ,3,3,3,7 R1 V1 h1 F +-0,4 N ,4 77,7 88, E M V e D5 S port A and B D3 D G1 C 34,5-0,17 M10-5H -0,18 f 16 17,5 37,68 44,03 M14-5H 23,5 64,66 M16 H with charge pump 12 cm3 (s 20-23), 33 cm3 ( ) H3 with charge pump 18 cm3 ( 20-23), 33 cm3 ( 24), 66 cm3 ( ) Port R gear pump M1, M2, Z2 7/8-14 UNF-2B 15/16 12 UN-2B 7/16-20 UNF- 2B, 15/16 12 UN-2B SE straight thread O -ring boss SAE flange, 1 1/4, 3000 psi, 4 thread 7/16-14 UNC-2B

9 Figure 8 Outline drawing for axial piston variable displacement pumps, Series 20, frame s Deviating control lever of servo valve in direction: A: Cause high pressure in A orifice in clockwise pump Cause high pressure in B orifice in counter clockwise pump B: Cause high pressure in B orifice in clockwise pump Cause high pressure in A orifice in counter clockwise pump

10 Figure 9: Hose flange A B C D 0,1 52,4 79,4 E 0,1,2 36,5 F 3/8-16 UNC 2A 5/8-11 UNC -2A G(Order No.) H Washer 10,2 Washer 16 J 22,5 30 C D 0,1 52,4 79,4 E 0,1,2 36,5 F 3/8-16 UNC 2A 5/8-11 UNC -2A G(Order No.) H Washer 10,2 Washer 16 J 22,5 30 Figure 10: Flange for piping A K B L M-0,1 8 12,6 N-0,1 2,8 2,8 O 39,7+0,05 53,9+0,01 P+0,2 4 4 U V5-104 V6-158 Note: Flange according to SAE J 518 c 20 24: 1, 5000 psi, torque screw tightening 3/8 16 UNC 2A: Nm : 1 ½,6000 psi torque screw tightening 5/8 11 UNC 2A: Nm

11 Type designation and order code:

12 HP Engineering s.r.o. Kuzmányho Turčianske Teplice Slovakia Phone: Fax: e mail: hpengineering@stonline.sk