1P Group 1 Hydraulic Gear Pumps Double 1P Pumps www.jbj.co.uk/gear-pumps.html #DriveLineHarmony 1PD 9.2 element can bear 14.8 Nmand 1PD 4.2 element can bear 4.5 Nm. Primary shaft check. You then have that the torque applied on the shaft of the first element will be the sum of the torques absorbed by the two pumps: For proper operation of Marzocchi 1Pdouble pumps, you need to comply with the following instructions: »The torque transmitted by the shaft of the first element is the sum of the torques transmitted by each single element. Absorbed torque Calculate necessary torque (M) of a pump subject to pressure differential between inlet and outlet as follows: M= (V •Dp) / (62.8 •hhm) [Nm] »element performance and features are the same as the elements of the corresponding single pumps. »Double pumpmax. rotation speed is determined by the lowest speed amongmax. rotation speeds of every single element. »check that power absorption of the front element is equal or higher than the rear element. »Operating pressures are limited by the max. torque transmissible by the shaft of the first element and by the shaft connecting the two elements one to the other. 3 V = displacement [cm /rotation] Dp = pressure differential [bar] hhm = hydromechanical efficiency (take 0.80 as indicative value under cold conditions and 0.85 under working conditions). 1P pumps are also available as double versions. Please contact our Sales-Technical Dept. for further details on specific configurations not explicitly indicated (flanges, shafts and so on). The torque of every single element can be determined with the following formula: Driving shaft absorbed torque. For a proper check of the shafts and of the max. torques that they can bear, see the following example: Let’s say that we should use a double pump 1P D 9.2 + 1P D 4.2 with max. pressure respectively of 150 bar and 100 bar. By making pressure values correspond to the sizes in the table on the side, we shall obtain as a result the following: 14.8 + 4.5 = 19.3 Nm Secondary shaft check. In our example the torque applied to the shaft of the second element (4.2 Nm) is allowed because it does not exceed the limit for that type of shaft (in this case, max. value would be 21.5 Nm). This value shall never go over the limit value allowed for that type of shaft (in this case, max. value would be 26.3 Nm). Max. Torque 21.5 Nm Max. Torque 21.5 Nm "G" SHAFT TAPERED SHAFT Max. Torque 26.3 Nm To block the coupling: n. 1 M7 nut, with a torque wrench setting fixed at 12 Nm. 0 2 4 6 8 10 12 14 16 18 20 0 50 100 150 200 250 p [bar] 11.5 9.2 7.5 6.7 5.8 5 1.6 2 2.5 3.3 4.2 M [Nm] 1P or 30
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