In all types of industrial and mobile machinery markets, downtime is costly, especially related to hydraulic leaks. In addition to the time required for the repair or replacement of leaking components, time is required to find the source of the leak and clean up the lost hydraulic fluid. Often the loss of production while the machine is out of service far exceeds these costs. Therefore, both the end user and the OEM are seeking alternatives to reduce the potential for hydraulic leaks.
In a tie-rod hydraulic cylinder design, the seals between the tube and the end caps are typically compressed by the tension created by the torque applied to the tie rods. If the tensile force on the tie rods decreases, the compression on the seal also decreases, resulting in leaks between the tube and end caps. Two common failure modes include stretched tie rods and unthreaded tie rod nuts. These failure modes are common, especially in high-duty cycle, high-pressure spikes, and high-vibration applications.
Welded construction cylinders from Aggressive Hydraulics are designed to significantly reduce the potential of these types of failures. On the base end, the end cap is welded to the tube which eliminates both the seal and the threaded connections. On the rod end, the static seal is located between the outside diameter (OD) of the head gland and the inner diameter (ID) of the tube. The head gland is tightened to the tube and an axial set screw is installed as a secondary means to prevent it from unthreading. The compression, and therefore the performance, of the static seal is not affected by the tightness of the head gland.
Aggressive Hydraulics welded cylinders have other advantages over tie rod type cylinders:
| Item | Tie-Rod | Welded |
|---|---|---|
| Port Position | 4 options at 90 degree increments, referred to as Position 1, 2, 3, etc. | Ports can be freely located around the circumference of the cylinder. |
| Port Location along body | Located in the end caps. | Typically located near the head and end cap, but can be freely located with the addition of welded tubes. |
| Envelope dimensions | Large square heads and end caps with tie rods along the tube, as well as nuts and washers extending beyond end caps. | Smaller footprint- typically limited to OD of the tube. |
| Cleanability | Difficult to clean because debris is captured between tie rods, tubes, and end caps. | Smooth exterior does not capture debris and is easily cleaned. |
| Rod mount | Standard male or female threads with mating mounts can unthread during operation. | Options for welded rod mounts instead of threaded for increased durability. |
| Linear sensors | External sensors that thread into the end cap are not protected from physical damage. | Options for fully embedded sensors which are protected inside the cylinder body. |
In addition to these design advantages, Aggressive Hydraulics welded cylinders lend themselves to application-specific customization. A few options that make a cylinder “Purpose Built” include:
- Integration of valves, including counterbalance valves, pilot-operated check valves, velocity fuses, or other combinations of cartridge valves.
- Seal selection based on the pressure, fluid, temperature, duty cycle, and other parameters.
- Wide variety of customized rod and base mounts.
- Integration of different types of linear position sensors, including embedded and external.
- Fixed cushions that prevent field tampering and can be designed to work at lower flow rates than spear-type cushions.
Contact us to discuss replacing tie-rod cylinders with Aggressive Hydraulics welded cylinders in your application.
