Figure-8 Bronze Washer

We provide custom manufacturing of finished bronze parts and self-lubricating bronze, precisely based on our clients’ drawings.

Precision Figure-8 bronze washer for pump wear applications

Custom Figure-8 Bronze Washers for Hydraulic Pump Wear Plates

In the intricate world of high-performance hydraulic systems, every minute component bears immense pressure and responsibility. Among these, the Figure-8 Bronze Washer for Hydraulic Pump Wear Plate (also known as a spectacle plate or side plate) stands out as an indispensable element in both gear and piston pumps. It not only dictates the volumetric efficiency of the pump but also directly influences the equipment’s operational lifespan.

The Core Material: Why Bronze?

The selection of material for hydraulic pump wear plates and thrust washers is paramount. The most common materials used for manufacturing Figure-8 Washers are High Leaded Tin Bronze or Bi-metal composites.

Chemical & Physical Properties

Typically, alloys such as C93200 (SAE 660) or C93700 (SAE 64) are employed. Their unique chemical compositions endow them with exceptional performance characteristics:
  • Copper (Cu, 80-88%): Provides excellent thermal conductivity, efficiently dissipating frictional heat generated by high-velocity hydraulic oil flow, thereby preventing pump overheating.
  • Tin (Sn, 3.5-11%): Enhances the alloy’s base strength and hardness, enabling it to withstand the impact loads from high-pressure hydraulic oil.
  • Lead (Pb, 5-25%): This is the most critical element. Lead exists in a free state within the copper matrix, forming a microscopic ‘self-lubricating film’ during friction. This characteristic is vital for reducing wear and friction.

Physical Performance Indicators

Property
Value / Rating
Significance in Hydraulic Pumps
Hardness (Brinell)
HB 60-90
Moderate hardness to protect mating steel parts from wear.
Tensile Strength
≥ 200 MPa
Sufficient to withstand high-pressure hydraulic shocks.
Thermal Conductivity
High (approx. 50-70 W/m·K)
Rapidly dissipates friction heat to maintain oil film stability.
Elongation
10-15%
Provides necessary conformability under shaft deflection.

Comparative Material Properties of Common Hydraulic Bronze Alloys

The selection of a specific bronze alloy is a function of the intended operating pressure, speed, and environmental exposure. The following data delineates the physical and mechanical properties of the most prevalent alloys used in the manufacture of figure-8 wear plates and thrust washers.

Alloy Designation Common Name Tensile Strength (PSI) Max Load (PSI) Max Speed (SFM) Key Applications
C93200 (SAE 660) Leaded Tin Bronze 35,000 4,000 750

General industrial pumps, gear bushings, and machine tools

C95400 Aluminum Bronze 85,000 High Moderate

Heavy-duty construction, marine pumps, and mining equipment

SAE 841 Sintered Bronze 26,500 2,000 1,200

Self-oiling applications, vacuum-impregnated washers

C90300 Phosphor Bronze 45,000 4,000 500

High-performance springs and heavy load bearings

C86300 Manganese Bronze 110,000 Very High Low

High-load, slow-speed pivoting points

Leaded tin bronze, particularly C93200, remains the industry standard for general utility in hydraulic gear pumps due to its exceptional machinability and the inherent lubricity provided by its lead content. The lead particles dispersed within the copper-tin matrix act as an internal lubricant; as the bearing surface heats up, a minute amount of lead smears across the interface, preventing metal-to-metal seizing. However, in environments requiring higher structural integrity or resistance to impact, aluminum bronze (C95400) is preferred for its superior tensile and yield strengths.

Figure-8 Bronze Washer for Hydraulic Pump Wear Plate
Figure-8 Bronze Washer for Hydraulic Pump Wear Plate

Performance Advantages: The Irreplaceable Role of Figure-8 Bronze Washers

Under the high-pressure conditions of hydraulic pumps, Figure-8 Bronze Washers exhibit the following core advantages:
•Exceptional Anti-Galling Properties: During start-up and shut-down, the oil film might not be fully formed. High leaded bronze possesses excellent anti-galling capabilities, preventing ‘cold welding’ with steel gears or shafts.
•Embeddability: Hydraulic systems inevitably contain tiny metal particles or impurities. The relatively softer bronze material can ’embed’ these hard particles into the washer’s surface, preventing them from scratching expensive gear shafts or pump housings.
•Conformability: Under high loads, shafts may experience slight deflections. The Figure-8 Bronze Washer can undergo microscopic deformation to adapt to shaft deviations, maintaining sealing performance and preventing internal leakage.
•Low Coefficient of Friction: Significantly reduces power loss during pump operation, enhancing mechanical efficiency.

The Mystery of the Figure-8 Design: Specific Application Areas

The Figure-8 Bronze Washer derives its name from its distinctive ‘8’-shaped appearance (also known as a spectacle plate).

Installation Location Of Figure-8 Bronze Washer

It is typically situated on both sides of the gears in a gear pump, sandwiched between the pump housing and the end cover, functioning as a side plate or wear plate.

Functional Logic

•Axial Sealing: Its primary role is to seal the gear end faces, preventing high-pressure oil from leaking from the high-pressure zone back to the low-pressure zone through the gear sides (internal leakage).
•Thrust Bearing: The pressure of the hydraulic oil pushes the gears towards the suction side, and the Figure-8 washer bears these radial and axial unbalanced forces.
•Pressure Compensation: Many high-end gear pumps utilize a ‘floating side plate’ design, where the Figure-8 Washer, under back pressure, tightly adheres to the gear end faces. This design automatically compensates for wear, maintaining high volumetric efficiency over time.

Why This Material in This Location?

Gears are typically made of hardened steel and operate at very high speeds (up to 2000-4000 RPM). If steel-on-steel contact were used in this area, it would instantly generate high temperatures and cause seizing. The Figure-8 Bronze Washer acts as a ‘sacrificial component,’ utilizing its self-lubricating and wear-reducing properties to protect the core gear set and pump body. The cost of replacing a washer is significantly lower than replacing the entire pump head.

Common Sizes and Types For Figure-8 Bronze Washer

The dimensions of Figure-8 Thrust Washers are entirely dependent on the pump model.

Material Selection Guide

Type
Construction
Best For
Key Advantage
Solid Cast Bronze
Single-piece alloy (C932/C937)
Heavy-duty, high-impact pumps
Maximum embeddability and heat dissipation.
Bi-metal (Steel Backed)
Steel shell with sintered bronze layer
Medium to high-pressure gear pumps
High structural strength and cost-efficiency.
Aluminum Bronze
Extreme pressure or corrosive environments
Superior load-bearing and corrosion resistance.

Key Dimensional Parameters

•Inner Diameter (ID): With precise tolerance for shaft fit.
•Thickness: Requires extremely high parallelism (typically within 0.005mm).
•Center Distance of the ‘8’ shape.

Bronzeoilless.com: Your Custom Manufacturing Experts

At Bronzeoilless.com, we understand that standard parts cannot meet all requirements, especially for the aftermarket and improved designs for specific operating conditions.
We support Custom Manufacturing:
Whether you need a single sample or batch production, we provide solutions:
  • Manufacture by Drawing: Simply send your CAD drawings (DWG/DXF) or PDF files, and we will perform precision machining according to your tolerance requirements.
  • Reverse Engineering from Samples: If drawings are unavailable, you can send us old samples, and we will use high-precision surveying equipment for reverse engineering.
  • Material Options: We offer various material choices, including C93200, C95400 (Aluminum Bronze), and bi-metal, to match your specific operating conditions.
  • CNC Precision Machining: Ensures the contour and parallelism of the Figure-8 meet OEM-level standards.
Choosing a high-quality Figure-8 Bronze Washer for your Hydraulic Pump Wear Plate is an investment in the longevity and reliability of your hydraulic system. Don’t let inferior washers compromise your pump’s performance.
Contact the Bronzeoilless.com team today, send us your drawings or requirements, and receive professional quotations and technical support. Let us provide lasting power assurance for your hydraulic pumps!
Custom CNC Oil-free Bearing Solutions

Custom Oil-Less Bearing Bushing

Self-lubricating bearing selection and drawing confirmation