Car Lift Repair Tampa Florida | The Hydraulic Pump Furthering Your Knowledge

Years ago, I recall a discussion with a fellow engineer from Car Lift Repair Tampa Florida regarding this matter. He conveyed the notion that the optimal pump inlet conditions are those of 100 percent boost. Essentially, the aim is to supercharge the pump inlet consistently across all operational scenarios.

While achieving such supercharging in practical terms is often unfeasible, there exists virtually no justification for not ensuring a flooded inlet. A flooded inlet implies a reservoir of oil positioned above the pump, ensuring its intake is submerged below the minimum oil level — as depicted in the inset image.

In the context of industrial power units, this necessitates avoiding the conventional practice of mounting the Car Lift Repair Tampa Florida pump atop the tank. Similarly, mounting the pump within the tank, particularly with a vertically positioned electric motor, is typically impractical unless the pump is fully submerged to a depth where its intake is beneath the minimum oil level, sans the need for a drop tube.

Both the aforementioned mounting configurations not only compel the pump to lift the oil but also significantly complicate maintenance efforts, with the setup inside the tank posing the greatest challenges. Unfortunately, despite the drawbacks for equipment owners, mounting the pump within the tank has almost become customary for electric power units due to its cost-effectiveness in construction.

Car Lift Repair Tampa Florida Variable-displacement pumps equipped with hydraulic or electro-hydraulic displacement control, or load-sensing control, offer the advantage of operating at low standby pressure. Essentially, when the pump is not actively dispensing output, it remains at a relatively low pressure, typically at zero flow except for the necessary compensation for internal leakage.

From an efficiency standpoint, the lower the standby pressure, the better, as any pressure drop due to leakage within the pump generates heat without contributing to useful work. This underscores the rationale behind maintaining a low standby pressure.

However, determining the optimal standby pressure poses a question. Is zero standby pressure the ideal scenario? For load-sensing pumps, maintaining a standby pressure below 15 bar (220 PSI) can lead to control instability, hence standby pressures lower than this threshold are generally advised against.

Car Lift Repair Tampa Florida Variable pumps equipped with hydraulic or electro-hydraulic displacement control possess the capability to stand by at zero flow and near-zero pressure without encountering control issues. Nevertheless, this presents a risk: without a certain amount of internal leakage (which necessitates some standby pressure), friction within the rotating components may cause the oil in the pump’s casing to overheat, potentially resulting in lubrication failure and seizure.

In essence, allowing the pump to operate completely unloaded for prolonged durations is generally inadvisable. In situations where this is likely to occur, it’s recommended to flush the pump’s housing to maintain proper cooling.

For instance, Rexroth suggests that if their A11VO series pumps remain on standby for more than 10 minutes with zero flow or at a pressure below 15 bar (220 PSI), the pump’s housing must be flushed at a rate of 2 to 6 L/min (0.5 to 1.6 gal/min) depending on the pump’s frame size. This indicates that if a standby pressure greater than 15 bar is sustained, flushing is unnecessary, as this level of pressure generates adequate internal leakage to prevent the oil temperature in the housing from reaching hazardous levels.

When crafting and designing a hydraulic tank, numerous factors demand attention. Among these considerations is ensuring the prevention of an air-sucking vortex, akin to what occurs when water spirals down a drain, from forming at the pump intake line penetration. To achieve this objective, the following measures should be implemented:

– Place the intake penetration a distance of at least five times its inside diameter from the nearest reservoir wall, and no less than half its inside diameter (or at least 100 mm or 4 inches) above the tank’s bottom.

– Guarantee that the intake penetration remains submerged at a depth of at least twice its inside diameter consistently.

– Opt for an intake line size such that the fluid velocity does not exceed 1.2 m/sec (4 ft/sec), preferably maintaining a slower velocity.

– Conclude the intake penetration within the tank with a bell-mouthed adapter or flared tube to reduce fluid velocity upon entry. This action also serves to diminish turbulence, promoting quieter pump operation.

– For flooded inlets, incorporate a vertical baffle along the intake penetration’s center line. (To assess the effectiveness of this approach, one can conduct a simple experiment: drain a sink of water, observe the formation of a vortex, and then introduce the experimental baffle to witness its impact.)

Recently, I was tasked with conducting a failure analysis on a Car Lift Repair Tampa Florida hydraulic motor that was the subject of a warranty claim. The motor had unexpectedly ceased operation after a mere 500 hours in service, falling short of its anticipated service life by approximately 7,000 hours.

Upon inspection, it became apparent that the motor’s bearings had failed due to inadequate lubrication, stemming from the motor being initiated with insufficient oil present in its housing.

A common misunderstanding among maintenance personnel with limited hydraulic training is the belief that, because oil circulates through Car Lift Repair Tampa Florida  hydraulic components during operation, no additional attention is necessary during installation beyond simply connecting hoses.

Following installation, it is imperative to fill the motor’s housing with clean hydraulic oil before connecting its case drain line. 

Some may speculate that the motor’s housing should naturally fill with hydraulic oil through internal leakage. While this may occur in most cases, it often transpires after the motor or pump has incurred damage. Unfortunately, this damage might not manifest until the component fails prematurely, potentially hundreds or even thousands of service hours later.

Car Lift Repair Tampa Florida Hydraulic components possess a distinctive quality in their ability to mitigate or counterbalance hydrostatic forces, thereby reducing the strain on lubricated surfaces. This reduction in surface loading enhances the maintenance of full-film (hydrodynamic) lubrication, thereby diminishing the likelihood of boundary lubrication conditions.

Hydrostatic force is determined by the product of pressure and area, expressed as F = P x a mathematically. Balancing or offsetting hydrostatic force is accomplished by subjecting opposing areas to identical pressure.