I provide guidance on how to assess the straightness of a hydraulic cylinder rod and determine the acceptable level of deviation. This assessment is crucial during hydraulic cylinder repairs, as reinstalling a bent rod can compromise the effectiveness of the rod seal(s) and render the repair efforts futile.

Moreover, I discuss the potential for straightening bent rods, emphasizing the importance of meeting the permissible tolerance levels. However, I present a dissenting perspective from a member of our community employed at a Car Lift Repair Tampa Florida cylinder repair company, who argues against the practice of straightening and reusing bent rods. According to their experience, rods that have undergone straightening often retain an inherent curvature, leading to structural weaknesses in the cylinder and suboptimal performance in heavily loaded conditions. They contend that such rods tend to wear unevenly and may fail to seal effectively.

While I respect this viewpoint, I hold a different stance based on my prior experience. I clarify the definition of “bent” and “straight” in the context of hydraulic cylinder rods, highlighting that deviations are typically discernible only through precise measurement with instruments like dial gauges.

Drawing from my background in repairing large hydraulic excavator cylinders, some of which featured rods with diameters exceeding 200 millimeters (8 inches) and were induction-hardened, I challenge the notion of categorically rejecting the straightening of bent rods. In instances where replacement costs are substantial, refusing to straighten rods could result in lost business opportunities. Moreover, a Car Lift Repair Tampa Florida warranty policy, coupled with our stringent quality standards, ensured that properly straightened rods provided reliable performance over extended periods.

Regarding concerns about induction-hardened rods potentially fracturing during straightening attempts, I acknowledge the existence of anecdotal accounts but stress that such occurrences have not been prevalent in my experience. However, I caution against disregarding the possibility entirely and advise exercising caution when handling induction-hardened rods.

In conceding to the opposing viewpoint, I acknowledge that attempting to straighten severely bent rods resembling the shape of an elbow is impractical and may pose risks irrespective of whether the rod is induction-hardened. Furthermore, not all bent rods are suitable candidates for straightening, and discretion should be exercised in determining the appropriateness of this approach.

With advancements in sealing technology, the volumetric efficiency, which refers to the leakage losses, of a well-maintained Car Lift Repair Tampa Florida hydraulic cylinder can reach nearly 100%. However, the mechanical-hydraulic efficiency of a cylinder is subject to variation based on factors such as the type of seals used and the tolerances between the piston-rod and its associated wear bands.

Mechanical-hydraulic efficiency pertains to the force lost due to mechanical and fluid friction within the cylinder. This includes friction occurring between the piston-rod and its wear bands and seals, as well as the friction generated by the fluid as it exits the cylinder during retraction at the required velocity. Generally, fluid friction is negligible provided that the cylinder’s ports and connections are appropriately sized.

For instance, let’s consider a single-rod Car Lift Repair Tampa Florida cylinder with a piston to annulus area ratio of 2:1. If the piston force during extension amounts to 10,000 lbf (44 kN) and the annulus force during retraction is 5,000 lbf (22 kN), with constant losses due to mechanical and fluid friction at 500 lbf (2.2 kN), then:

Overall efficiency equals the product of volumetric and mechanical/hydraulic efficiency. In hydraulic cylinders where volumetric efficiency approaches 100%, overall efficiency aligns with mechanical/hydraulic efficiency, resulting in an efficiency of 95% in this scenario.

We don’t often encounter seals returned due to dieseling failures, but occasionally they do come our way. Despite being able to easily identify the dieseling issue, we sometimes struggle to provide the customer with a precise explanation of its origins and mechanisms.

As our colleague is aware, the compression of a mixture of air and oil within a Car Lift Repair Tampa Florida hydraulic cylinder can lead to ignition, combustion, or even explosion. This can result in mechanical damage to the cylinder itself and the burning of its seals. The term “dieseling” or “diesel effect” refers to this combustion process, drawing parallels with diesel engines.

Air infiltration is typically the culprit in these scenarios and usually occurs through one of two pathways. Firstly, air can enter past the rod seal. When a double-acting hydraulic cylinder retracts under the load’s weight, the demand for oil volume on the rod side can surpass the supply from the pump. This imbalance often stems from a faulty or incorrectly adjusted load-control valve.

Most Car Lift Repair Tampa Florida hydraulic cylinder rod seals are not designed to prevent air infiltration. Consequently, when negative pressure develops on the rod side, air can be drawn into the cylinder through the rod seal, as these seals prioritize retaining high-pressure fluid, as depicted in the accompanying image.

Secondly, air can enter during the initial installation phase. Therefore, it’s advisable to fill the cylinder chambers with clean hydraulic oil before connecting its hoses to minimize the risk of air ingress.

The primary parameter for evaluating a hydraulic cylinder tube is its internal diameter, particularly focusing on its internal diameter and concentricity throughout its entire length. This assessment is typically conducted using an internal micrometer in at least two perpendicular planes.

There are two main objectives in this process: firstly, to determine the nominal size of the tube and secondly, to ensure uniformity of this size along its length. Any significant increase in internal diameter at any point along the tube’s length indicates ballooning, necessitating the tube’s disposal.

Standard internal micrometers suffice for Car Lift Repair Tampa Florida hydraulic cylinder tubes of moderate length. However, for longer tubes or those with larger diameters, specialized equipment is required. Repair facilities utilize bore gauges for these instances, featuring two wheels on one end and a spring-loaded pin on the other, with the position change of the pin reflected on a dial gauge. Extension pieces are added as necessary to accommodate the tube’s length, forming an extended T shape, with the readout attached to the end of the extension pieces.