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M–2210–SRev. 2/93 PVH Piston Pumps Including Controls Vickers® Piston PumpsOverhaul Manual M–2210–SRev. 2/93 Section 1 – Introduction A. Purpose of Manual This manual describes basic operating characteristics and provides overhaul information for the Vickers PVH 57/74/98/131 series piston pumps. The information contained herein pertains to the latest design series as shown in the model code. B. Related Publications Installation dimensions for the PVH series pumps and controls are not included in this manual. Individual parts numbers for the basic pumps are also not included. Refer to the related publication list below for publications that include this type of information. PVH57 Service drawing M–2206–S PVH74 Service drawing M–2207–S PVH98 Service drawing M–2208–S PVH131 Service drawing M–2209–S PVH Series Application GB–C–2010 C. Model Code Description Variations within each basic model series are covered in the model code as shown on the next page. Service inquires should always include the complete unit model code number as stamped on the name plate, and the assembly number as stamped on the mounting flange. M–2210–SRev. 2/93 Model Code N = ISO 3014/2- Short straight E32N keyed 1 = SAE ”C” Straight (J744-32-1) keyed 2 = SAE “C”� Splined 14 tooth (J744-32-4) 12/24 D.P. 3 = SAE “CC” Splined 17 tooth (J744-38-4) 12/24 D.P. 12 = SAE “D” Splined 13 tooth (J744-44-4) 8/16 D.P. 13 = SAE “C Straight (J744-38-1) keyed 16 = SAE “D“ Straight (J744-44-1) keyed Blank = Non-thru-drive (single pump) A = Thru-drive pump with SAE “A” 2-bolt rear flange mounting (SAE J744-82-2) B = Thru- drive pump with SAE “B” 2- and 4-bolt rear flange mountings♦ (SAE J744-101-2/4) C = Thru-drive pump with SAE “C” 2- and 4-bolt rear flange mountings♦(SAE J744-127-2/4) S = Adjustable maximum volume stop (non-thru-drive and non-torque-control pumps only) PVH *** QI * – * (*) * – ** * – 10 – C(M) ** (**) (**) – *0 – *** ** = Customer desired torque limiter setting specified in ten bar (145 psi) increments, e.g.: 8 = 80 bar (1160 psi); 18 = 180 bar (2610 psi). The torque setting range is from 30–80% of the specified compensator setting. C = 70-250 bar (1015-3625 psi) (standard) CM = 40-130 bar ((580-1885 psi) (optional QI version) IC = Industrial control UV = Unloading valve control for accumulator circuits Shaft seal, prime mover end S = Single, one-way (standard) D = Double, two-way (optional) Recommended on second pump of tandem assembly (PVH**/ PVH**) Maximum geometric displacement 4 6 8 10 57 = 57.4 cm3/r (3.5 in3/r) 74 = 73.7 cm3/r (4.5 in3/r) 98 = 98.3 cm3/r (6.0 in3/r) 131 = 131.1 cm3/r (8.0 in3/r) 7 11 Mounting flange, prime mover end C = SAE “C” 4–bolt type (SAE J744-127-4 ) M = ISO 3019/2–125B4HW (Option for PVH57QI and PVH/74QI only) R = Right hand, clockwise (Standard on QI models) L = Left hand, counterclockwise (Optional on QI models) Configuration Main ports F = SAE 4-bolt flange pads (standard ) M = SAE 4-bolt pads with metric mounting bolt threads (PVH57 & PVH74 only) Shaft-end type, at prime mover end 9 Pump design number Pressure compensator adjustment range Mobile pumps Industrial pumps Shaft rotation, viewed at prime mover end 5 2 3 4 5 6 7 8 9 11 12 132 PVH *** - C – * (*) * – ** * – 10 – C ** (**) (**) – *0 – *** 1410 Additional control functions13 Blank = No additional controls V = Load sensing, 20 bar differential pressure setting T = Torque limiter VT = Load sensing and torque limiter Torque limiter factory setting14 15 Control design number 31 = C, CM, or C**V controls. 13 = C**T controls 14 = C**VT controls 10 = UV and IC controls ♦ Built from pump with SAE “A” rear pad to which suitable flange adapter is bolted. For best availability and flexibility, order PVH SAE “A” thru-drive pump and SAE “B” or “C” adapter kit separately. 10 (Subject to change. Installation dimensions unaltered for design numbers 10 to 19 inclusive. ) 2 4 5 6 7 8 9 10 13 14 15 15 12 25 = Normal factory setting of 250 bar for “C” models. 7 = Normal factory setting of 70 bar for “CM” models. Pressure compensator factory setting in tens of bar 16 Special features suffix 027= Composite 2-bolt/4-bolt mounting conforming to SAE “C” (except PVH131) 031= Thru-drive SAE “A” pad cover 041= No case-to-inlet relief (for use with supercharged circuits) 057= Shaft-up operation (vertical mount) Torque restrictions apply to #2 shaft in PVH74 and 98 thru-drive, and PVH131 single and thru-drive, pumps. Vickers is not responsible for misapplied usage of these shafts. Please contact a Vickers representative for review of your application. � 111 Piston pump, variable displacement 1 1 3 12 16 3 Industrial version 16 M–2210–SRev. 2/93 Section 2 – Description A. Basic Pump Figure 1 shows the basic construction of the PVH series piston pump. Major parts include the drive shaft, housing, yoke, rotating group, valve plate, control piston, bias piston, valve block and compensator control. The PVH series replaces the pintle bearing assembly with saddle bearings, which reduces weight and eliminates the roller bearings that added to maintenance time and overhaul costs. B. Pump Controls Two common pump control types are available. One type is the standard “C” compensator control that limits pump outlet pressure to a desired level. The other type is the “CV” pressure limiter/load sensing control. Now available is the “IC” (Industrial Control) which can be used as a load sensing compensator, remote compensator control and electrohydraulic control. These limit pump outlet pressure and also regulate pump displacement to match load requirements. Section 3 – Principles of Operation A. Pump Operation Rotation of the pump drive shaft causes the cylinder block, shoe plate and pistons to rotate (See Figure 2). The piston shoes are held against the yoke face by the shoe plate. The angle of the yoke face creates a reciprocating motion to each piston within the cylinder block. Inlet and outlet ports connect to a kidney slotted wafer plate. As the pistons move out of the cylinder block, a vacuum is created and fluid is forced into the void by atmospheric pressure. The fluid moves with the cylinder block past the intake kidney slot. The motion of the piston reverses and fluid is pushed out of the cylinder block into the outlet port. Warning Before breaking a circuit connection, make certain that power is off and system pressure has been released. Lower all vertical cylinders, discharge accumulators, and block any load whose movement could generate pressure. Plug all removed units and cap all lines to prevent the entry of dirt into the system. Outlet valve plate kidney slot Valve block Figure 1. PVH Section View Piston Shoe plate Figure 2. PVH Pump Operation Yoke faceOutlet port Inlet port Cylinder block Drive shaft Valve plate Inlet valve plate kidney slot Drive shaft Yoke Control piston Inlet Valve block Bias piston Piston M–2210–SRev. 2/93 Principles of Operation B. Pump Controls Pressure Compensator Controls “C” & “CM” (Figure 3) The standard “C” and low pressure “CM” compensator controls are internally pilot operated, spring offset, 2-way valves. Their purpose is to limit system pressure to a desired level by varying pump displacement. These controls only provide the flow required to satisfy the load demand, while maintaining a constant preset pressure. During operation, load or system pressure is continually fed to the bias piston. The function of the bias piston is to maintain the yoke at a full pump displacement position. Load or system pressure is also fed to the compensator spool chamber within the control. Pressure within the compensator spool chamber acts upon the spring force of the compensator spring. When load or system pressure is below the pressure setting of the compensator spring, the compensator spool remains offset and the pump continues to operate at full displacement. When load or system pressure approaches the compensator pressure setting, the compensator spool will start to move and overcome the compensator spring force. Fluid will then meter into the control piston area. Since the control piston area is greater than that of the bias piston, the control piston pushes the yoke towards minimum pump displacement. The compensator control continues to meter fluid to the control piston, adjusting the pump displacement, and pumping only enough fluid to satisfy the load demand while holding the system at a constant pressure. When load or system pressure exceeds the compensator setting, the compensator spool shifts towards the spring chamber area. A maximum amount of fluid is then metered to the control piston area, causing the yoke to shift to minimum pump displacement. When system pressure decreases below the compensator pressure setting, the compensator spool returns to its original position and the yoke returns to maintain maximum pump displacement. The compensator is available in two pressure ranges. The “C” spring has an adjustment range of 70–250 bar (1015–3625 psi). The “CM” spring has an adjustment range of 40–130 bar (580–1885 psi). Figure 3. “C” & “CM” Controls I Dr P Body Pressure limiting adjustment SpringTo tank Pressure limiting spool Control piston Yoke angleBias piston Piston pump Load Sensing & Pressure Compensator Control C(M)*V (Figure 4) This pump will provide power matching of pump output to system load demand, maximizing efficiency and improving load metering characteristics of any directional control valve installed between the pump and the load. Load sensing ensures that the pump always provides only the amount of flow needed by the load. At the same time, the pump operating pressure adjusts to the actual load pressure plus a pressure differential required for the control action. Typically, the differential pressure is that between the pressure inlet and service port of a proportionally controlled directional valve, or a load sensing directional control valve. When the system is not demanding power, the load sense control can operate in an energy-saving stand-by mode. To achieve the low pressure, no flow, stand-by mode, the load sense signal line must be drained to the tank externally. The standard differential pressure setting for load sense is 20 bar (290 psi), but can be adjusted to between 17 and 30 bar (247 and 435 psi) on the pump. M–2210–SRev. 2/93 Principles of Operation If the load pressure exceeds the system pressure setting, the pressure compensator de-strokes the pump. The load sensing line must be as short as possible and can also be used for remote control or unloading of the pump pressure. For remote control, it is recommended that you contact your Vickers representative for the correct configuration of the control. Figure 4: C(M)*V Control Inlet Load sense signal port Outlet To load 1.7 bar (25 psi) Case drain PVH with UV Control for Accumulator Circuits (Figure 5) This pump control functions as a load- sensing pressure compensator that unloads the pump at a preset pressure and loads the pump after preset pressure drop. Figure 5: UV Control • Inlet Case drain Outlet 1.7 bar (25 psi) Pump Pressure compensa- tor with load sensing (C**V control) Unloading valve • • • • • • • • To accumulator Pressure & Torque Limiter Control C**T (Figure 6) This pump senses pressure and flow and starts destroking at a predetermined input torque level. The rate of flow reduction is normally tailored to follow the maximum power capability curve of the prime mover. Input torque is limited while the pressure compensator limits the system pressure. When the input speed remains constant (i.e. industrial drives), the torque limiter acts as an input power limiter. This allows a smaller electric motor to be used if maximum pressure and maximum flow are not required at the same time. At low load levels, the control permits high pump displacement and high load speeds. Under heavy loads, speed is reduced, preventing stalling of the prime mover. In the case of variable speed drives (I.C. engines), this function provides, in addition to pressure compensation or limiting, a torque limiting ability that can be adjusted to the torque/speed characteristics of the engine. The start of torque limiting (pump-destroking) is pressure dependent. The pressure is selectable (see model code) and is factory preset to between 30% and 80% of the maximum pressure control setting. The adjustment range for the “C” compensator is 80 to 200 bar (1160 to 2900 psi) in 10 bar (145 psi) increments. There is no “CM” spring option available with the torque limiting control. Figure 6: C**T Control Inlet Case drain Outlet To load 1.7 bar (25 psi) Torque Limiting Plus Load Sensing Control C**VT (Figure 7) This pump control option functions like a load sensing control, but with additional torque limiting tailored to the size of the drive motor selected. The limiting function is the same as for a pressure compensator with torque limiting. The combination of the two controls provides the following benefits: M–2210–SRev. 2/93 Principles of Operation 1. The energy savings of a variable displacement load sensing control. 2. The pump pressure follows the load pressure. 3. The torque control allows smaller drive motors to be used. 4. The pressure compensator de-strokes the pump as maximum pressure is reached. 5. The pump pressure can also be remotely controlled using the load sense line. The C**VT control allows complete control of flow and pressure, either mechanically or electrically, if used with proportional valves. Figure 7: C**VT Control Case drain Inlet Load sense signal port To load Outlet 1.7 bar (25 psi) Industrial Control (Figures 8 & 9) This pump control option is intended for use when multiple, remote, or electrically controlled compensating settings, with or without load sensing, are desired. Pressure compensation is obtained by removing an internal plug, keeping the load-sense signal port plugged, and internally applying pilot pressure to the spring chamber of the pilot-operated control spool. For pressure compensation with load sensing, the internal plug stays, the load-sense signal port is unplugged, and pilot pressure is externally applied. An external relief valve is used to set system pressure. The externally adjustable control-spool spring determines the differential pressure setting of the pump control. Pilot (spring chamber) pressure is separated from outlet pressure by an internal orifice. Outlet pressure shifts the spool when pressure drop across the orifice reaches the differential pressure setting, and the pump de-strokes. The relief valve can be mounted to an NFPA-D03/ISO 4401-03 pad on the pump control, or remotely located via tapping and blanking plates installed on the pad. The standard factory-set differential pressure setting of the pump control is 20 bar (290 psi) and is not specified in the pump model code. Any other ordered differential pressure, within the control’s adjustable pressure range of 17–35 bar (247–508 psi), will be specified in the model code following the “IC” control code; for example, “-IC30-” for a 30 bar setting. Application examples: Mounting Control Type � EHST Electrical control compensator � DG valve w/DGMC Double or triple compensator � C–175 Remote control relief valve � CGE–02 Electrical relief valve Figure 8: Industrial Control Section View Orifice Removable plug Control adjustment screw Locknut Pilot chamber Control spool Plug Spring guide Plug Case To control piston Pump outlet Load sense port M–2210–SRev. 2/93 Principles of Operation Figure 9: Industrial Control Case drain Pressure compensating without load sensing Pressure compensating with load sensing Case drain Inlet Outlet To load 1.7 bar (25 psi) Tank port Pressure port • • • • X Load sense signal port Inlet Load sense signal port Outlet To load 1.7 bar (25 psi) X Tank port Pressure port • • • • C. Load Sensing/Pressure Limiting Operation As one would expect from the title, this control is a combination of the features of both the pressure limiting and load sensing controls. Refer to Figure 10. The load sensing spool senses the pressure difference (pressure drop ∆P) between pump outlet and load pressure across a series flow control or system directional valve which is inherent in its operation. This differential pressure causes the load sensing spool to move against its spring to the closed–center position. If the differential pressure (pressure drop ∆P) increases (greater flow through the series valve), the load sensing spool moves to the right. This opens discharge to the control piston. Outlet pressure at the control piston strokes the yoke toward a lower flow and when differential pressure again causes the load sensing spool to move to the closed-center position. If differential pressure lowers (less flow through the series valve), the load sensing spool moves to the left, opening the control piston to tank. The bias piston then strokes the yoke toward a higher flow. When differential pressure (pressure drop), increases enough to move the load sensing spool to the closed-center position, yoke movement will stop and flow will remain constant. Figure 10: Load Sensing Control System (A) Load Pressure Signal Load Sensing Spool Load Load Sensing Adj. Compensator Adjustment Pressure Limiting Spool To Tank Flow Control or Dir. Valve Control Piston Piston PumpBias Piston The load sensing portion of the control operates as a function of the pressure drop across the series valves (pressure drop ∆P), and is independent of system pressure. It establishes a constant flow characteristic from the pump based on the magnitude of the directional valve opening (operator controlled). If outlet pressure increases to the maximum pressure limit setting, the pressure limiting spool meters fluid to the control piston. The control piston moves the yoke to reduce flow. If outlet pressure continues to rise, the spool will continue to meter fluid to the control piston and the pump will stroke to zero flow at maximum pressure. M–2210–SRev. 2/93 Principles of Operation Reduced horsepower standby feature When the system flow control valve or directional valve is closed completely, the circuit is placed in standby. Note This feature assumes the system flow control valve or directional valve provides decompression of load sensing pressure in the standby, fully closed position. Pressure at point A (Figures 10 & 11) must decay toward zero through the system flow control or directional valve for standby to occur. Decompression of the load sensing pressure allows the pump to stroke to zero flow and minimum pressure. The circuit functions in the following manner. Assume the flow control or directional valve is closed and there is no bleed of point A (Figure 10) to tank. The fluid is trapped and the load sensing spool is held to the left by the spring. The system pressure rises until the pressure limiting spool takes over. The yoke then stokes to zero flow and holds pressure at the maximum limiter setting. If, in the closed condition, the flow control or system directional valve bleeds point A (Figures 10 & 11) to tank, the load sensing feedback pressure