As the end of the month approached, an OEM customer alerted their hydraulic cylinder manufacturer about a persistent squealing noise coming from the boom extension cylinder on a rough terrain forklift. The Automotive Lift Repair Tampa Florida single-stage cylinder, with a 6″ bore, 3″ rod, and 14′ stroke, was causing a major issue since the OEM had 80 machines that couldn’t ship by the deadline due to this audible problem. The OEM demanded that the cylinder manufacturer send a team to replace all 80 cylinders immediately.

So, what could be causing this issue? Seal stick and slip? Excessive stroke speed? Internal leakage? Load-control valve? What else could be at fault? How would you handle this situation?

The squealing was evident at all engine speeds, ruling out flow rate or stroke speed as the cause. I systematically isolated or replaced all cylinder valves with no change in the noise.

I removed a Automotive Lift Repair Tampa Florida cylinder from a machine and tested it on a bench with quick disconnects. Even after removing the rod seal and running the cylinder under no load, the squeal persisted. Removing the piston seal didn’t help either. The squeal continued even without any seals installed.

Reinstalling the Automotive Lift Repair Tampa Florida seals and connecting the cylinder to an older machine (the ‘yard machine’) while it was still on the bench, the squeal disappeared. When I drained the oil and reconnected the cylinder to the new machine, the squeal returned, indicating the cylinder was not the issue.

Despite the OEM’s insistence on replacing all 80 cylinders, I requested an additional day to pinpoint the root cause. Observing the drained oil’s appearance and a slight hissing sound when removing the head gland led me to suspect aeration.

The next step was proving to the customer’s engineers that the air was coming from the oil. I investigated if there were changes in the new machine model, such as the pump, hydraulic tank design, suction lines, or strainer. The answer was no.

I then asked if there were any changes in oil viscosity, brand, supplier, or formula. Again, the answer was no. I was convinced that air in the hydraulic fluid was causing the squeal. The oil vendor was contacted and confirmed that the oil’s formula had changed, specifically the air-release additive had been reduced. 

I procured Automotive Lift Repair Tampa Florida hydraulic oil additive, added a quart to a machine with the squeal, and the noise disappeared within 5 minutes. This confirmed that the oil was the problem. With the oil formula adjustment made, all 80 machines were able to ship on time.”

– Always store the cylinder fully retracted.

– Keep it indoors in a clean, dry area.

– Apply grease to the internal surfaces of eye/clevis bushes or bearings, especially if they are steel.

– Protect any exposed chrome on the rod. Petroleum jelly-impregnated tape, like Denso tape, is suitable for this. Note: Applying Denso tape when the rod is not fully retracted can damage the rod seal upon retraction.

– Use steel plugs, not plastic, to cover the service ports with plugs or blanking plates.

– Consider filling the Automotive Lift Repair Tampa Florida cylinder with clean hydraulic oil through its rod-end service port, particularly if it’s a costly, large-diameter, or high-pressure cylinder. Be aware of some considerations before doing this.

An unfilled cylinder will contain air, which, if not completely dry, can condense into moisture as temperatures drop. This moisture can cause spot rusting and pitting inside the cylinder tube, reducing the cylinder’s volumetric efficiency, the piston seal’s lifespan, and ultimately the tube’s durability.

Filling the cylinder with clean hydraulic oil can prevent these issues, but there are precautions to take:

For example, if a cylinder is stored in winter at 10°C and later exposed to summer temperatures of 40°C, the oil pressure increase can be significant. Using the formula:

The pressure could rise to 354 bar or 5134 PSI. This can lead to unexpected issues when the mechanic opens the service ports.

– Ensure that potential temperature increases will not cause the pressure to exceed the cylinder’s working pressure.

– Only fill the cylinder when it is fully retracted and only through the rod-end port to prevent dangerous pressure intensification.

– Use service port plugs or blanks rated for the cylinder’s working pressure.

– Provide a method to check and vent any pressure before removing the service port blanks. This can be done by fitting each port blank with a pressure test point, allowing quick attachment of a pressure gauge to monitor and safely vent the pressure if necessary.

How should a hydraulic cylinder be positioned for both short-term and long-term storage? At our company, which repairs and evaluates hydraulic cylinders and their associated failures, we handle around 1,000 cylinders annually. We focus on providing solutions for breakdowns and repairing those that have failed.

One recurring issue we’ve encountered is seal failure, especially in large pneumatic and Automotive Lift Repair Tampa Florida hydraulic cylinders. We’ve observed that storing cylinders flat has a direct impact on piston and rod seal longevity. As a result, we’ve established a storage standard that follows your recommendations for plugging ports and wrapping rods, but also requires that all cylinders be stored vertically. This vertical orientation helps prevent distortion and ensures that the weight of the cylinder does not stress the rod seals, ultimately benefiting the piston seals as well. I’d be interested to hear your thoughts on this matter.

From my perspective, I deliberately left this out to avoid reinforcing what I see as a myth. Based on my experience, the idea that vertical storage is crucial is unfounded. I recall two cases involving large, 400-ton mining excavator cylinders weighing between two and three tons, with piston rods alone weighing over a ton.

Imagine handling a Automotive Lift Repair Tampa Florida three-ton cylinder with a four-meter length and storing it vertically to prevent it from toppling over or causing injury. This is challenging and impractical. Consider a truck transporting the cylinder over 1,000 miles of rough terrain. If vertical storage is crucial, shouldn’t the cylinder be transported in the same orientation? The truck driver might think this is unreasonable but might agree to do so for a higher fee.