P31 Parker Gear Pump 3000 PSI 2400 RPM Dump Truck

Product Overview

The Parker P31 / PGP031 is part of Parker Commercial Hydraulics’ PGP030/031 cast-iron external gear pump series, developed for mobile hydraulics, construction equipment, agricultural machinery, material handling systems and demanding refuse/dump truck applications.

Parker’s official catalogue identifies the PGP030/031 family as single and multiple pumps and motors, with series capability up to approximately 41 GPM, 3000 psi and 2400 rpm.

P31 is not a single displacement pump. The PGP031 platform is available with several gear widths, each providing a different displacement and maximum pressure rating. Parker lists PGP031 displacement options from approximately 1.97 in³/rev (32.3 cm³/rev) to 3.94 in³/rev (64.6 cm³/rev), with maximum pressure ranging from 3000 psi to 2500 psi depending on gear width.

The platform also supports multiple shaft configurations, SAE mounting options, several port standards and single or tandem/multiple pump configurations. These characteristics make the PGP031 particularly useful for replacement projects where dimensional and hydraulic compatibility are critical.

For replacement applications, the complete pump configuration must be verified, including gear width, rotation, shaft, mounting, ports, pump arrangement and pressure duty.

We engineer replacement units around the original pump configuration and perform 100% simulated working-condition testing to verify flow, pressure, leakage, operating stability and overall performance.

Technical Specifications

Parker P31 / PGP031

• Brand: Parker Commercial Hydraulics / Parker Hannifin
• Series: PGP030/031
• Model Family: P31 / PGP031
• Pump Type: Fixed-displacement external gear pump
• Construction: Cast-iron gear pump
• Maximum Series Flow: Approximately 41 GPM
• Maximum Series Pressure: 3000 psi (approximately 207 bar)
• Maximum Series Speed: 2400 rpm
• Pump Arrangement: Single or multiple/tandem
• Control Method: Fixed displacement
• Gear Width / Displacement Options:
  • 1 inch: 1.97 in³/rev ≈ 32.3 cm³/rev
  • 1¼ inch: 2.46 in³/rev ≈ 40.4 cm³/rev
  • 1½ inch: 2.96 in³/rev ≈ 48.5 cm³/rev
  • 1¾ inch: 3.45 in³/rev ≈ 56.5 cm³/rev
  • 2 inch: 3.94 in³/rev ≈ 64.6 cm³/rev
• PGP031 Maximum Pressure:
  • 1 inch: 3000 psi
  • 1¼ inch: 3000 psi
  • 1½ inch: 3000 psi
  • 1¾ inch: 2500 psi
  • 2 inch: 2500 psi
• Available Shaft Types: SAE “C” spline, SAE “C” keyed, SAE “B” spline, SAE “B-B” keyed and other configurations depending on ordering code.
• Mounting: Multiple SAE mounting configurations
• Porting: NPT, O.D. tube, split flange, BSPP and metric straight thread options
• Rotation: CW / CCW according to complete ordering code
• Approximate Single-Pump Weight: About 12–14.5 kg depending on gear width, before accounting for configuration differences.

Pressure Rating by Gear Width

Parker does not define one universal continuous pressure rating for the entire P31/PGP031 range. The maximum pressure depends on gear housing code and gear width. For PGP031, 1-, 1¼- and 1½-inch gear widths are listed up to 3000 psi, while 1¾- and 2-inch gear widths are listed up to 2500 psi.

Theoretical Flow

Theoretical flow can be calculated using:

Qₜ = Vg × n / 1000

For PGP031:

32.3 cm³/rev configuration

• 1000 rpm: 32.3 L/min
• 1500 rpm: 48.5 L/min
• 2000 rpm: 64.6 L/min
• 2400 rpm: 77.5 L/min

40.4 cm³/rev configuration

• 1000 rpm: 40.4 L/min
• 1500 rpm: 60.6 L/min
• 2000 rpm: 80.8 L/min
• 2400 rpm: 97.0 L/min

These are theoretical displacement-flow values. Actual pump output is affected by pressure, oil temperature, viscosity, volumetric efficiency and pump wear. Parker states that its published performance data represents average laboratory results from production units rather than guaranteed performance of every individual unit.

Key Technical Advantages

1. Heavy-Duty Cast-Iron Construction

The Parker PGP030/031 platform was developed for demanding hydraulic applications including construction, refuse/dump trucks, material handling, forestry, agriculture and industrial equipment. Its heavy-duty gear-pump architecture is well suited to mobile machinery.

2. Up to 3000 psi

Selected PGP031 gear-width configurations are rated up to 3000 psi / 207 bar. Larger gear widths have lower maximum pressure ratings, so the actual pressure limit must always be selected from the complete housing code.

3. Up to 2400 rpm

The official Parker catalogue specifies a maximum series speed of 2400 rpm for PGP030/031. This makes the range compatible with many vehicle and PTO-driven hydraulic systems when the actual operating speed remains within the specified limit.

4. Multiple Shaft Configurations

Parker offers several shaft choices including SAE A, B, BB and C configurations, with spline and keyed versions. For tandem pumps, shaft strength and Parker’s PL factor must also be checked.

5. Single and Tandem Pump Capability

The PGP platform is designed for single and multiple pumps. When multiple sections share a common drive shaft, the shaft must withstand the total transmitted input power. Parker therefore specifies PL limits for different shaft designs.

6. Flexible Porting Options

The Parker ordering system provides NPT, ODT, split-flange, BSPP and metric straight-thread port options, allowing the PGP031 platform to be integrated into a wide range of hydraulic systems.

Related PGP Models

The original title also includes PGP030, PGP031, PGP050, PGP051, PGP075 and PGP076. These should not share one specification set.

PGP050/051

Parker’s official documentation lists:

• PGP050 gear widths from approximately ½ to 2½ inches.
• Displacements from approximately 20.9 to 104.5 cm³/rev.
• PGP050 maximum pressure from approximately 172 to 138 bar, depending on gear width.
• PGP051 uses the same displacement range, while selected configurations reach 207 bar.
• Maximum speed: 2400 rpm.

PGP075/076

Parker also lists:

• PGP075 displacement from approximately 67 to 201 cm³/rev.
• PGP075 maximum pressure of approximately 2500, 2250 or 2000 psi, depending on gear width.
• PGP076 displacement from approximately 67 to 168 cm³/rev.
• PGP076 maximum pressure up to 3000 psi, with lower ratings for larger gear widths.
• Maximum series speed: 2400 rpm.

Therefore:

P31 ≠ P76 ≠ PGP050 ≠ PGP075.

They represent different frame/section configurations within the Parker PGP platform.

Application Areas

Parker’s official catalogue identifies PGP030/031, PGP050/051 and PGP075/076 applications including:

• Dump trucks
• Refuse trucks
• Construction machinery
• Material-handling equipment
• Forestry equipment
• Agricultural machinery
• Industrial hydraulic systems
• Winch systems
• Flow-divider systems
• Priority-valve systems
• Two-speed valve systems
• Piggyback pump systems

Parker specifically lists refuse/dump truck applications, providing direct manufacturer-level support for positioning P31/PGP031 as a dump-truck hydraulic pump.

Expert Maintenance Tips

1. Verify Rotation from the Complete Ordering Code

Parker explains the rotation convention by viewing the shaft toward the observer with the idler gear beneath the drive gear. Clockwise and counter-clockwise configurations generate opposite flow directions. Inverting the pump changes port orientation but does not change shaft rotation.

2. Do Not Order by “P31” Alone

PGP031 has several gear-width options. The 32.3, 40.4, 48.5, 56.5 and 64.6 cm³/rev configurations have different pressure capabilities. The gear housing code must therefore be confirmed before replacement.

3. Verify PTO Speed on Dump Trucks

The official series limit is 2400 rpm. Check PTO, transmission and engine-driven shaft speed to ensure the actual pump speed stays within the specified limit.

4. Check the PL Factor on Tandem Pumps

In multiple-pump configurations, the entire input power is transmitted through the common shaft. Parker requires the PL factor to be calculated using pressure and total gear width and kept within the shaft-specific limit.

5. Do Not Randomly Restrict the Pressure Port

Parker specifically notes that certain port configurations are intended only for low-pressure inlet service and that NPT ports are not recommended above 1500 psi. Port selection must therefore follow the complete Parker port code.

6. Flush the Hydraulic System After a Pump Failure

Parker’s service manual emphasizes cleanliness. If a pump failure may have introduced metal particles into the circuit, the hydraulic oil should be drained, the complete system flushed, filter screens cleaned or replaced, and new oil installed.

7. Recheck the Relief Valve During Commissioning

Parker’s service procedure calls for an accurate pressure gauge when adjusting the relief-valve pressure setting and specifies controlled start-up procedures for new or rebuilt pumps.