Parker PGP503 Series Fixed Displacement External Gear Pump

Product Description

The PGP503 belongs to Parker PGP500 aluminium gear pump platform. It is a compact, high-pressure fixed-displacement external gear pump for mobile hydraulics. Its matching gear motor variant is PGM503. Adopting 9-tooth gear profile, this pump features low flow pulsation and quiet running. Different from cast iron PGP350/PGP365, PGP503 uses high-strength aluminium housing for lightweight and good heat dissipation. Single and tandem multi-section configurations are available, widely used for small-to-medium mobile hydraulic systems with strict space and weight limits.

1. Overview

PGP503 is an external-mesh fixed displacement gear pump with pressure-balanced thrust plates and journal bearing design. The optimized 9-tooth gear profile reduces pulsation and noise. Its modular construction offers flexible options for mounting flanges, shaft ends, port styles, seal materials and integrated valves. Clockwise (CW) and counter-clockwise (CCW) rotation versions are standard. It is a preferred high-pressure compact pump for mobile machinery.

2. Construction & Key Features

1. High-strength aluminium housing: Light weight, excellent thermal conductivity and sufficient rigidity for compact mobile installations.
2. Pressure-balanced thrust plates: Automatically compensate axial clearance, retain high volumetric efficiency throughout service life and reduce friction and wear.
3. Journal bearing design: Fluid-lubricated bearings provide reliable load capacity for continuous operation. Axial thrust on the shaft is not allowed. Outboard bearing versions are optional for heavy radial load conditions.
4. Precision ground 9-tooth gear set: Optimized tooth geometry, low flow ripple, quiet operation, volumetric efficiency up to 96%.
5. Modular design: Wide selection of SAE flanges, shaft ends, inlet/outlet ports and seal options. Tandem multi-pump assembly is supported to feed independent hydraulic circuits from one drive source.
6. Integrated valve options:
   • Relief valve with anti-cavitation check valve
   • Priority flow valve
   • Load-sensing unloading valve
   • Solenoid unloading relief valve, cross relief valve, etc.

3. Main Technical Specifications

• Displacement range: 0.8 ~ 7.9 cm³/rev (code: 0008, 0012, 0016, 0021, 0025, 0033, 0036, 0043, 0048, 0058, 0062, 0079)
• Max continuous pressure: up to 275 bar (3988 psi); pressure rating decreases for larger displacement models
• Max intermittent pressure: up to 300 bar (4351 psi)
• Speed range: 500 ~ 4000 rpm (max speed reduces on large displacement codes)
• Rotation: CW / CCW
• Standard mounting: SAE A 2-bolt flange, rectangular through-bolt flange; custom flanges available on request
• Shaft options: keyed shaft, SAE splined shaft
• Port options: SAE split flange, SAE straight thread, BSPP, metric thread; side or rear port layout
• Compatible fluid: Anti-wear mineral hydraulic oil. FPM fluorocarbon seals optional for water-glycol, emulsion and fire-resistant fluids; FPM seals are mandatory for phosphate ester fluids.
• Recommended viscosity: 16 ~ 100 cSt
• Suction requirement: Minimum absolute inlet pressure ≥0.8 bar to avoid cavitation
• Weight: approx. 2.0 ~ 3.8 kg (depends on displacement and configuration)

4. Typical Applications

• Compact construction machinery: mini excavators, small skid steer loaders, compact aerial work platforms
• Agricultural equipment: planters, small harvesters, tractor auxiliary hydraulic circuits
• Material handling: pallet trucks, small tailgate lifts, compact lifting units
• Mobile hydraulic power packs, small forestry machines and mini sanitation vehicles

5. Ordering Code Explanation

Example model: PGP503B0036BP3D1NE3E3

• PGP503: Series identifier (PGM503 = matching gear motor)
• A: Single pump; B: Tandem / multi-section pump
• 0036: Displacement code
• C / E: Rotation (CCW / CW)
• P3: Flange code
• D1: Shaft type code
• N: Seal material code
• E3E3: Port configuration
• Suffix codes: integrated valve, revision version

Note: Verify port layout, shaft diameter, rotation direction and built-in valves before pump replacement.

6. Operation Guidelines

1. Direct drive by flexible coupling is recommended. Avoid excessive radial shaft loads; select outboard bearing version if significant radial force exists.
2. Suction line must be sized adequately. Keep low inlet pressure drop to prevent cavitation damage to thrust plates and gear sets.
3. Recommended filtration: 10 μm hydraulic filter. Regular oil change is required. Although tolerant to contamination, solid particles accelerate thrust plate wear.
4. Built-in relief valve is only for system protection. It is NOT designed for continuous throttling or pressure regulation duty.
5. For tandem pumps, each section has its independent pressure rating. Check displacement and pressure separately for every section during selection.

7. Differentiation from Related Series

• PGP503: Aluminium housing, 9-tooth gear, small displacement, compact high-pressure pump
• PGP502: Compact aluminium pump, similar frame, different internal gear profile
• PGP505 / PGP511 / PGP517: Larger frame sizes in PGP500 aluminium family
• PGP350 / PGP365: Cast iron heavy-duty pumps for higher flow and rugged mobile applications
• PGM503: Gear motor sharing identical housing, cannot be used as a pump