Bypass Function
In some applications it is desirable to bypass fluid around the variable displacement pump when pump
shaft rotation is either not possible or not desired. For example, an inoperable vehicle may be moved to a
service or repair location or winched onto a trailer without operating the prime mover. To provide for
this, Series 90 pumps are designed with a bypass function.
The bypass is operated by mechanically rotating the bypass hex on both multifunction valves three (3)
turns counterclockwise (CCW). This connects working loop A and B and allows fluid to circulate without
rotating the pump and prime mover.
Warning
Excessive speeds and extended load/vehicle movement must be avoided while moving in bypass
function. The load or vehicle should be moved not more than 20 % of maximum speed and for a duration
not exceeding 3 minutes. Damage to drive motor(s) is possible. When the bypass function is no longer
needed care should be taken to re-seat the HPRV hex plugs to the normal operating position.
Warning
Possible pump and/or motor damage.
Bypass valves are intended for moving a machine or vehicle for very short distances at very slow speeds.
They are NOT intended as tow valves.
Auxiliary Mounting Pads
Auxiliary mounting pad specifications
Mounting pad Option code Spline coupling Frame size/Maximum torque N•m [lbf•ft]
042 055 075 100 130 180 250
SAE A AB 9T 16/32 169 [125] 93 [69] 97 [72] 97 [72] 106 [78] 120 [89] 120 [89]
SAE B BC 13T 16/32 283 [209] 204 [150] 211 [156] 211 [156] 334 [246] 324 [239] 324 [239]
SAE B-B BB 15T 16/32 301 [222] 342 [252] 281 [207] 281 [207] 368 [271] 368 [271] 368 [271]
SAE C CD 14T 12/24 n/a 408 [301] 447 [330] 447 [330] 741 [546] 628 [463] 624 [460]
SAE D DE 13T 8/16 n/a n/a n/a n/a 741 [546] 1070 [789] 1070 [789]
SAE E EF 13T 8/16 n/a n/a n/a n/a n/a 1070 [789] 1070 [789]
SAE E EG 27T 16/32 n/a n/a n/a n/a n/a 1220 [900] 1220 [900]
Mating pump requirements
The accompanying drawing provides the dimensions for the auxiliary pump mounting flange and shaft.
Pump mounting flanges and shafts with the dimensions noted below are compatible with the auxiliary
mounting pads on the Series 90 pumps. An O-ring is required when a pump is bolted to an aux pad. Refer
to outline drawings for more details and O-ring dimensions.
Technical Information
Series 90 Axial Piston Pumps
Features and Options
520L0603 • Rev 0804 • March 2016 41
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