Do you know that feeling? You lift a heavy pallet with your front loader (Tur), turn off the tractor, and after a few minutes, you notice the load slowly falling to the ground. You've already replaced the cylinder seals, bought a new distributor, and the machine still won't hold.
Many mechanics tear their hair out over this, searching for leaks. However, the problem is rarely a defect—it's usually just... the laws of physics.
BRhydraulic experts explain why a classic hydraulic system will always leak and show how one small valve can solve this problem forever.
1. Why won't the new distributor hold the weight?
Most agricultural and construction machinery uses slide valves. A steel slider slides inside the cast iron body to direct the oil.
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The hard truth about sliders: For the slider to move at all within the housing, there must be a microscopic gap (play) between them. Oil under pressure (exerted by the weight hanging on the cylinder) will slowly leak back into the reservoir through this gap.
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Conclusion: Even a brand new, top-of-the-line slide gate can slowly "loose" the load over time. If someone demands that the gate hold the pallet in the air all night long, precisely to the millimeter, they're asking for the impossible.
2. Hydraulic lock (twin check valve) – Problem solution
If you want the actuator to stay in place as if it were set in concrete, you need to use a so-called hydraulic lock (technically: a twin-acting controlled check valve).
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How does it work? The lock is mounted on the lines between the distributor and the actuator (ideally as close to the actuator itself as possible, e.g., on steel tubing). Inside, it has sealed poppet/ball valves.
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Resting phase: When you release the distributor lever, the valves in the cylinder close immediately. The oil is locked in the cylinder against the wall. No weight can force it out, because poppet valves (unlike slide valves) guarantee 100% tightness.
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Movement Phase: So how do you lower the arm? When you pull the lever, the pump forces oil into one chamber of the actuator. This oil pressure also acts on an internal piston in the slide, which mechanically "pushes" the second valve, allowing oil from the opposite chamber to flow freely back.
3. Disaster Protection (When the Hose Bursts)
Hydraulic locks aren't just convenient; they're also, above all, safe . Imagine lifting an excavator arm with a heavy load over a car, and the old rubber hose between the distributor and the cylinder suddenly breaks.
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Lockless System: All the oil in the actuator quickly escapes through the ruptured hose and the arm falls to the ground, destroying everything underneath.
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Locking system (mounted on the cylinder): A hose rupture causes a pressure drop. The locking mechanism immediately snaps shut, locking the oil in the cylinder. The boom remains safely in the air! For this reason, regulations require the use of such valves on all machines that lift loads above people (e.g., HDS, aerial work platforms).
Summary
Don't blindly replace another pump or distributor if your cylinder is slowly sagging. Install a hydraulic lock on your lines and enjoy precise operation and complete safety. At BRhydraulic, you'll find reliable hydraulic locks (twin check valves) adapted to any flow rate and thread size.
