Bosch Rexroth AZPF Gear Pump

The Bosch Rexroth AZPF Gear Pump is a fixed displacement external gear pump. It has a gear wheel pair and housing with a front and rear cover.

The Bosch Rexroth AZPF Gear Pump is available in a range of sizes across two series:

• Series 1X, standard version pump: 4 | 5 | 8 | 11 | 14 | 16 | 19 | 22 cc/rev
  
• Series 2X, high performance, Platform F pump: 4 | 5 | 8 | 11 | 14 | 16 | 19 | 22 | 25 | 28 cc/rev
  

 
What is the primary task of an External Gear Pump?

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 and Silence Plus. Further configuration variants are given by different flanges, shafts, valve arrangements and multiple pump combinations. 

How is the Rexroth Gear Pump Constructed?

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 pressuried 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. 

Pumping principle

Due to the teeth moving apart during the rotation from the tooth mesh, the gear chambers become clear. The resulting negative pressure as well as the atmospheric pressure on the hydraulic fluid level in the reservoir cause hydraulic fluid to flow from the reservoir to the pump. This hydraulic fluid fills the gear chambers and is transported in them in the direction of the arrow (see sectional drawing) along the housing from the suction side to the pressure side. The teeth mesh again then, force the hydraulic fluid out of the gear chambers and prevent it from flowing back to the suction chamber.

 
Bosch Rexroth AZPF Gear Pump Construction

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

The drive shaft protrudes from the front cover where it is usually sealed by the shaft seal. The bearing forces are absorbed by slide bearings. These bearings were designed for high pressures and have excellent emergency running properties, especially at low rotational speeds. 

The gear wheels have 12 teeth. This keeps both flow pulsation and noise emission to a minimum. The sealing of the pressure chambers is achieved by forces depending on the working pressure. This ensures optimum efficiency. The working pressure generated in the gear chambers is transferred to the outside of the bearing bushings in specifically designed pressure fields in such a way that they are pressed against the gears and seal them up. The pressurized compression areas are limited by special seals. The seal in the area between the gear teeth and the housing is ensured by the smallest of gaps that are set depending on the pressure between the gear teeth and housing.

 
External Gear Pump Layout

• Snap ring 
  
• Shaft seal 
  
• Front cover 
  
• Slide bearings 
  
• Centering pin 
  
• Gear wheel 
  
• Drive shaft 
  
• Housing seal ring
  
• Pump housing
  
• Bearing bushing
  
• Axial field seal
  
• Supporting element 
  
• Rear cover 
  
• Torx screws 
  

WE ARE A BOSCH REXROTH CERTIFIED EXCELLENCE PARTNER

To enquire about Bosch Rexroth AZPF Gear Pumps and technical help with multiple Bosch Rexroth pump configuration options, please contact VHS Hydraulic Components on: 0114 276 4430   / E: info@hydraulic-components.net or visit our website at: https://www.hydraulic-components.net

You can also view the Bosch Rexroth AZPF External Gear Pump Technical Data Sheet at: https://www.boschrexroth.com/en/gb/products/product-groups/industrial-hydraulics/pumps/external-gear-pumps/azpf