Rexroth Pump
Rexroth Gear Pump
  • Description
  • Technique Feature
  • Specification
  • Applied Range

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Data Sheet of Rexroth gear pump AZPB
Data Sheet of Rexroth gear pump AZPF
Data Sheet of Rexroth gear pump AZPG
Data Sheet of Rexroth gear pump PGH-4X
 

 

External gear pump High Performance AZPF

Product description/General information

It is the central task of external gear pumps to convert mechanical energy (torque and speed) into hydraulic energy (flow and pressure). To reduce heat losses, Rexroth’s external gear units offer very high efficiencies. They are realized by pressure-dependent gap sealing and highly precise production technology.

 

Rexroth external gear pumps are built in four frame sizes: Platform B, F, N and G. Within each platform different displacements can be realized by different gear widths. The pumps are available in the versions Standard, High-Performance, SILENCE und SILENCE PLUS. Further configuration variants are given by different flanges, shafts, valve arrangements and multiple pump combinations.

Construction

The external gear pump consists essentially of a pair of gear wheels supported in bearing bushes and the housing with a front and a rear cover.

The drive shaft protrudes from the front cover where it is usually sealed by the shaft seal ring. The bearing forces are absorbed by slide bearings. These are designed for high pressures and have excellent dry-running qualities, especially at low rotational speeds. The gear wheels have 12 teeth. This keeps both flow pulsation and noise emission to a minimum.

The internal sealing of the pressure chambers is achieved by operating pressure-dependent forces. This ensures optimum efficiency. On the outer face, the movable bearing bushes are pressurized with operating pressure and pressed as seals against the gear wheels. Special seals form the boundary of the pressurized zone. The radial sealing at the tips of the gear teeth against the case is provided by smallest possible gaps that are formed pressure-dependent between the gear wheels and the housing.

Assembly external gear pump

 

 

1

Snap ring

8

Housing seal ring

2

Shaft seal

9

Pump housing

3

Front cover

10

Bearing bushing

4

Slide bearings

11

Axial field seal

5

Centering pin

12

Supporting element

6

Gear wheel

13

Rear cover

7

Drive shaft

14

Torx screws

 

Gear pumps with integrated valves

In order to reduce piping complexity, a flow control valve or pressure-relief valve can be integrated in the cover of the gear pump. Such solutions are used, for instance, for the hydraulic oil supply of power steering systems. The pump delivers a constant flow irrespective of the rotational speed. The residual flow is either returned internally to the suction port or distributed externally to other consumers.

 

3-way flow control valve, residual flow returned in suction line

qconst = 2 to 30 l/min

 

3-way flow control valve, residual flow distributed externally; loadable

qconst = 2 to 30 l/min

 

3-way flow control valve with pressure relief valve, residual flow returned in suction line

qconst = 2 to 30 l/min; p1 = 100 to 180 bar

 

Pressure relief valve, pressure guide in suction line

p1 = 5 to 250 bar

 

 

 

 

 

 

 

Internal gear pump, fixed displacement PGH-3X

Product description

Set-up

Hydraulic pumps of type PGH.-3X are gap-compensated internal gear pumps with constant displacement.

They basically comprise of: Mounting flange (1), housing (2), cover with through-drive (3), pinion shaft (4), internal gear (5), plain bearings (6), axial washers (7) and stop pin (8) as well as the radial compensation consisting of segment (9), segment support (10) and the seal rolls (11).

 

Suction and displacement procedure

The hydrodynamically mounted pinion shaft (4) drives the internally geared internal gear (5) in the direction of rotation shown.

The tooth clearances opening in the suction range suck in the fluid. The fluid is transported into the tooth clearances of pinion and internal gear, from the suction range (S) into the pressure range (P).

There, the fluid is displaced from the closing tooth clearances and delivered into the pressure port (P).

Suction and pressure range are separated by the radial compensation elements (9 to 11) and the tooth engagement between internal gear and pinion shaft.

Axial compensation

The displacement area in the pressure range is axially sealed by axial washers (7).

To the sides of the axial washers facing away from the displacement area a pressure field (12) is applied. These fields balance the axial washers vis-à-vis the displacement area, which results in a perfect sealing with low mechanical losses.

 

Radial compensation

The radial compensation elements consist of segment (9), segment support (10) and seal rolls (11).

Segment (9) and segment support (10) are arranged in the pressure field so that the resulting compressive force is basically accepted by the stop pin.

A small compressive force component presses segment and segment support onto the tooth tips of pinion shaft and internal gear and in this way provides for the sealing of the pressure range to the suction range with automatic clearance adjustment.

This is the prerequisite for constantly high volumetric efficiency during the entire operating time.

The clearance adjustment of segment and segment support is made possible by the seal rolls located inbetween.

Hydrodynamic and hydrostatic mounting

The pinion shaft (4) is accepted by hydrodynamically lubricated radial plain bearings (6).

The internal gear (5) is mounted hydrostatically in the housing.

Gear tooth system

The gear tooth system with involute edges has a large meshing length for little flow and pressure pulsation and thus guarantees low-noise running.

 

PGH-type hydraulic pumps are gap-compensated internal gear pumps with fixed displacement. The hydrodynamically mounted pinion shaft drives the internal gear. The pinion shaft and internal gear tooth clearances opening in the suction range suck in the hydraulic fluid and transport it to the pressure range. The suction and pressure range are separated by the radial compensation elements and the tooth engagement between the internal gear and pinion shaft.

 

Note

Safety requirements pertaining to the whole systems are to be observed.
Please contact us for applications with frequent load changes.

Pressure definition

  p1: Continuous pressure max.
  p2: Intermittent pressure max.
  p3: Pressure peaks max.

Determining the operating characteristics

Flow

[l/min]

Torque

[Nm]

Power

[kW]

Key

Vg

Displacement per revolution [cm3]

Δp

Differential pressure [bar]

n

Rotational speed [rpm]

ηv

Volumetric efficiency

ηhm

Hydraulic-mechanical efficiency

ηt

Total efficiency (ηt = ηv • ηhm)

Note

You can find diagrams for a rough calculation in chapter "Diagrams / Characteristic curves".

General technical data

Weight

m

kg

See chapter Dimensions

Installation position

No restrictions

Mounting type

Flange or through-bolting with spigot

Line connections

See chapter Dimensions

Direction of rotation, viewed on drive shaft

Clockwise or counter-clockwise, the pump may only be driven in the direction indicated

Drive shaft loading

Axial and radial forces only after consultation

Ambient temperature range

ϑ

°C

-30 to +80 with NBR seals (NBR = nitrile rubber)

-20 to +110 with FKM seals (FKM = fluoroelastomer)

Hydraulic fluids

The external gear unit is designed for operation with mineral oil according to DIN 51524, 1-3. Under higher load, however, Bosch Rexroth recommends at least HLP compliant with DIN 51524 Part 2.

Application instructions and requirements for hydraulic fluids should be taken from the following data sheets before the start of project planning:

 

Other hydraulic fluids on request.

Explanatory note regarding the selection of hydraulic fluid

The hydraulic fluid should be selected such that the operating viscosity in the operating temperature range is within the optimum range (vopt see selection diagram).

Viscosity and temperature of hydraulic fluids

Viscosity range

Permissible in continuous operation

ν = 12 … 800 mm²/s

Recommended in continuous operation

νopt = 20 … 100 mm²/s

Permissible for cold start

νmax ≤ 2000 mm²/s

Temperature range

With NBR seals (NBR = nitrile rubber)

ϑ = -30 °C … +80 °C

With FKM seals (FKM = fluoroelastomer)

ϑ = -20 °C … +110 °C

Observe the instructions for the filtration of the hydraulic fluid (see chapter Project planning information).

 

Direction of rotation

The dimensional drawings in the chapter Dimensions represent pumps for clockwise rotation. The position of the drive shaft or the position of suction and pressure port changes for counter-clockwise rotation.

Direction of rotation, viewed on drive shaft

Drives

1. Elastic couplings

The coupling must not transfer any radial and axial forces onto the pump.
The maximum admissible radial run-out deviation from the shaft to the fitting slot is 0.2 mm.
Admissible shaft shifting see installation information of the coupling manufacturers.

2. Coupling sleeve

To be used on splined shaft profile according to DIN and SAE
Attention: No radial or axial forces are permitted on the pump shaft or coupling sleeve. The coupling sleeve must be free to move axially.
The distance between the pump drive shaft and drive shaft on the customer side must be 2+1 mm
Provide installation space for the snap ring.

 

External gear pump High Performance AZPF

Features

- Consistent high quality based on large-volume production

- Long service life

- Slide bearings for high loads

- Drive shafts according to ISO or SAE and customer-specific solutions

- Line ports: connection flange or screw thread

- Combination of several pumps possible

 

 

Internal gear pump, fixed displacement PGH-3X

Features

- Fixed displacement

- Low operating noise

- Low flow pulsation

- High efficiency also at low speed and viscosity due to sealing gap compensation

- Suitable for broad viscosity and speed ranges

- All frame sizes and sizes can be combined with each other

- Can be combined with axial piston pumps, internal gear pumps and vane pumps

- Suitable for operation with HFC fluid (seal design “W”)

Use:

For fatigue-resistant drives with high power and high pressures with very large numbers of load cycles, e.g. plastics processing machines, automatable presses, casting machines and other applications with accumulator charging operation

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