Identifying and Rebuilding a Non-Original Steering Cylinder on a Case 580B

[MikePhua]

The Case 580B and Its Hydraulic Steering System
The Case 580B backhoe-loader, produced during the 1970s and early 1980s, was part of Case Corporation’s highly successful 580 series. Known for its mechanical simplicity and rugged design, the 580B featured a hydraulic steering system powered by a gear-driven pump. This system used dual steering cylinders mounted on the front axle to provide responsive control under load. The original cylinders were built to Case specifications, typically using imperial dimensions and seal profiles tailored to the machine’s operating pressure and fluid characteristics.
Over the decades, many 580B units have undergone repairs and retrofits, often involving aftermarket or non-OEM components. One common issue arises when a replacement steering cylinder—visually similar to the original—is installed but uses metric dimensions, complicating seal replacement and identification.
Challenges of Identifying a Non-OEM Cylinder
When a steering cylinder appears similar to the factory unit but features a rod diameter of 18 mm instead of the standard 19 mm (¾ inch), it’s likely an aftermarket or cross-manufacturer replacement. These cylinders may have been sourced from European suppliers or fabricated locally to fit the mounting geometry but differ internally in seal groove dimensions, rod finish, and pressure ratings.
Key identification challenges include:

• Absence of stamped manufacturer markings on the barrel
  
• Metric seal dimensions not matching standard Case part numbers
  
• Uncertainty about pressure tolerance and seal compatibility
  
• Difficulty sourcing small-quantity seals for non-standard sizes
  

In such cases, relying solely on visual comparison or part catalogs is insufficient. Instead, measuring the rod, bore, and seal grooves precisely is essential for sourcing replacements.
Seal Sourcing and Specification Matching
The seals found in the cylinder may be marked with dimensions such as:

• Rod seal: 18×26×5 mm
  
• Wiper seal: 18×28×5/7 mm
  

These measurements refer to:

• Inner diameter (ID): matching the rod
  
• Outer diameter (OD): fitting the gland bore
  
• Thickness or height: determining axial compression
  

To source replacements, hydraulic seal suppliers often require these exact dimensions, along with the seal type:

• V-seal (single-lip or double-lip)
  
• U-cup
  
• Wiper (scraper) seal
  
• O-ring with backup ring
  

While some suppliers offer online catalogs with metric listings, local hydraulic shops may be able to match seals from stock or order them in small quantities. European vendors often carry metric seals more readily than North American shops, which lean toward imperial sizing.
Pressure Ratings and Material Selection
One concern when replacing seals is pressure tolerance. A standard V-seal rated for 2,000 psi may seem low, but steering systems typically operate at much lower pressures than loader or backhoe circuits. In the Case 580B, steering pressure is often under 200 psi, making standard nitrile or polyurethane seals sufficient.
However, if the cylinder is used in a modified application or subjected to higher loads, consider upgrading to:

• Polyurethane seals rated for 3,000+ psi
  
• PTFE backup rings for extrusion resistance
  
• Double-lip wipers for improved contamination control
  

Always verify the material compatibility with hydraulic fluid type and operating temperature range.
Inspection and Manufacturer Clues
If seal replacement proves difficult, inspect the cylinder barrel for any stamped markings or etched logos. Cleaning the surface with solvent and a soft cloth may reveal hidden identifiers. Some manufacturers include part numbers or batch codes near the gland or mounting ears.
If no markings are found, consider disassembling the cylinder and photographing the internal components. Sharing these images with a hydraulic specialist can help match the gland design and seal stack to known profiles.
Field Anecdotes and Practical Advice
A technician in Stockholm encountered a steering cylinder on a 580B with metric seals and no visible branding. After extensive searching, he located a local webshop offering compatible seals based on measured dimensions. Though the rod seal was rated for only 2,000 psi, it performed adequately due to the low-pressure nature of the steering circuit.
In another case, a machinist in Pennsylvania rebuilt a similar cylinder using custom-cut seals from a bulk roll of polyurethane. He used a lathe to trim the OD and thickness, achieving a snug fit and restoring steering function without sourcing OEM parts.
Alternative Solutions and Preventative Measures
If seal sourcing proves impossible, consider:

• Replacing the entire cylinder with a verified OEM or aftermarket unit
  
• Retrofitting a cylinder from a known model like the Case 580 Super E, ensuring compatibility with mounting and stroke
  
• Installing a pressure gauge in the steering circuit to monitor system health
  

To prevent future issues:

• Document all replacement parts and dimensions during disassembly
  
• Keep spare seals on hand for known non-standard components
  
• Use thread sealant and torque specs when reassembling gland nuts and fittings
  

Conclusion
Identifying and rebuilding a non-original steering cylinder on a Case 580B requires a blend of measurement precision, hydraulic knowledge, and sourcing creativity. While metric dimensions complicate the process, low-pressure steering systems offer flexibility in seal selection. With careful inspection and the right supplier, even obscure cylinders can be restored to reliable service—keeping vintage machines like the 580B working hard for decades to come.