To correctly mount a hydraulic cylinder involves selecting the appropriate mounting style based on the application's specific requirements, such as load type, required movement, and environmental conditions. Proper mounting ensures optimal performance, extends the cylinder's lifespan, and maintains system safety.
Hydraulic cylinders are versatile components that convert hydraulic energy into linear motion. Their effectiveness heavily relies on how they are attached to their machinery. An incorrectly mounted cylinder can lead to misalignment, premature wear, structural damage, and operational inefficiencies. The primary goal of any mounting style is to securely connect the cylinder to the machine while accommodating its motion and the forces it generates.
Key Principles of Mounting
- Load Alignment: Ensure the cylinder's centerline is aligned with the load's direction of force to prevent side loading on the rod and seals.
- Structural Integrity: The mounting points and the machine structure must be strong enough to withstand the maximum forces exerted by the cylinder.
- Maintenance Access: Allow for easy inspection, maintenance, and replacement of the cylinder.
- Thermal Expansion: Account for potential expansion or contraction due to temperature changes, especially in long stroke applications.
Common Hydraulic Cylinder Mounting Types
Various mounting styles are available, each offering distinct advantages for different applications.
1. Trunnion Mount
The trunnion mount is a popular choice for applications requiring angular movement from the cylinder. As discussed in foundational lessons on hydraulic cylinder mounting, such as the segment indicating "And the trunian mount. And that is it for this lesson", the trunnion mount is a key method for accommodating arcing motions.
- How it Works: Trunnion mounts consist of pivot pins (trunnions) attached to the cylinder barrel, typically near the middle. These pins fit into bearings on the machine structure, allowing the cylinder body to pivot as the rod extends and retracts.
- Applications: Ideal for mobile equipment, construction machinery (e.g., excavator arms), and applications where the cylinder's body needs to rotate with the load.
- Advantages:
- Accommodates pivoting motion.
- Reduces side loading on the rod and seals, especially in applications with varying angles.
- Often used with clevis mounts at the rod end for full articulation.
- Considerations: Requires robust support structures for the trunnion pins and bearings. Eccentric loading can create bending moments on the cylinder barrel if not properly supported.
2. Flange Mounts
Flange mounts provide a strong, rigid connection, making them suitable for applications with straight-line force requirements.
- Head Flange Mount: Attached to the cylinder's head (rod end) and bolted directly to a machine surface. Provides excellent resistance to off-center loads and is ideal for pushing applications.
- Cap Flange Mount: Attached to the cylinder's cap (blind end) and bolted to a machine surface. Best for pulling applications or when the cylinder body needs to be contained within a recess.
- Advantages: Offer high rigidity, precise alignment, and excellent resistance to thrust.
- Considerations: Requires accurate machining of mounting surfaces for proper alignment.
3. Clevis and Eye Mounts
These mounts are designed for applications where the cylinder needs to pivot at one or both ends, similar to a hinge.
- Clevis Mount (Cap Clevis): Features a U-shaped bracket at the cap end that accepts a pin, allowing the cylinder to pivot. Often paired with a rod clevis or eye.
- Rod Clevis: A U-shaped bracket attached to the rod end, also accepting a pin for pivoting.
- Eye Mount (Cap Eye / Rod Eye): Similar to a clevis but with a single eyelet (or loop) that accepts a pin.
- Advantages: Accommodate angular movement, simple to install, cost-effective.
- Considerations: Primarily handle tensile (pulling) forces; less effective at resisting bending or side loads unless supported by a trunnion or similar intermediate mount.
4. Foot Mounts (Lug Mounts)
Foot mounts, also known as lug mounts, attach the cylinder to a flat surface using mounting feet or lugs.
- Side Lug Mount: Lugs extend from the side of the cylinder barrel. Can be offset from the centerline.
- Centerline Lug Mount: Lugs are aligned with the cylinder's centerline, providing more balanced force distribution.
- Advantages: Easy to install, widely adaptable for various applications.
- Considerations: Prone to side loading if not properly aligned. Requires careful consideration of the mounting surface's flatness and rigidity.
Summary of Common Mounting Types
| Mounting Type | Description | Typical Application | Advantages | Considerations |
|---|---|---|---|---|
| Trunnion Mount | Pivot pins located on the cylinder barrel | Mobile machinery, construction equipment | Accommodates angular movement, reduces side loads | Requires strong support structure, potential bending |
| Flange Mounts | Bolted to machine structure at head or cap end | Machine tools, presses, heavy industrial applications | High rigidity, precise alignment, resists thrust | Requires accurate machining of mounting surfaces |
| Clevis/Eye Mounts | U-shaped bracket or single eyelet for pin connection | Agriculture, mobile hydraulics, gates | Allows pivoting, simple, cost-effective | Best for tensile loads, less resistance to bending |
| Foot (Lug) Mounts | Lugs/feet extend from the cylinder barrel for surface mounting | Industrial machinery, general manufacturing | Easy to install, adaptable | Susceptible to side loading if misaligned |
Selecting the Right Mounting Style
When choosing how to mount a hydraulic cylinder, consider the following:
- Type of Load: Is it a pushing, pulling, or oscillating load?
- Magnitude of Force: How much force will the cylinder exert, and can the mounting support it?
- Stroke Length: Longer strokes may require more flexible mounts or intermediate supports.
- Operating Environment: Temperature, vibration, and contaminants can affect mount choice.
- Space Constraints: Physical space available for mounting.
- Precision Requirements: How critical is alignment and repeatable motion?
Installation Best Practices
Regardless of the mounting type chosen, proper installation is paramount:
- Ensure Proper Alignment: Misalignment is a leading cause of cylinder failure. Use shims or adjustable brackets if necessary.
- Use Appropriate Fasteners: Select bolts and nuts of the correct grade and size, and torque them to specifications.
- Clean Mounting Surfaces: Ensure surfaces are free of debris, rust, and paint for a secure fit.
- Allow for Movement: For mounts that pivot, ensure free movement without binding.
- Regular Inspection: Periodically check mounting bolts for tightness and inspect for signs of wear or damage.
By carefully considering the application and following best practices, you can effectively mount a hydraulic cylinder for reliable and efficient operation.
