Upward movements of a jack handle draw oil from the reservoir into the plunger cavity. The hydraulic pressure keeps the valve closed, and keeps the oil in the plunger cavity. When performing a downward stroke, the oil is released into the cylinder, forcing the ram — which in turn raises the saddle. Sometimes the oil escapes. Oil leaks can be corrected by the control of parts and after some maintenance procedures.
The most common failures on hydraulic jacks
Hydraulic cylinders can be subject to different types of failures. The two most common are the following.
Torsion of the stem
In case of resistance too intense during the deployment of the cylinder, the rod may be twisted. In this case, there are two ways to restore it.
Either we proceed to replace it. If the cylinder is standard, then order the part from the supplier. Otherwise, you can also use a specialist to machine the rod to replace it.
Second option: it corrects its positioning, which is generally possible only when the twist is light. It is usually used parallel turns, heavy equipment that often requires going through a professional.
Leakage of the cylinder
This is the most common breakdown that can be encountered. This can be external, that is to say, that the liquid can be seen escaping outside the cylinder, or internal: the fluid flows out of the chamber under pressure. If, in the first case, it is very easy to identify, in the second case is much harder to spot.
The leading causes of leakage are two in number.
It may, for example, be wear of the rod or cylinder. We are talking about micro-scratches on the metal surfaces of these parts that are sufficient to cause leakage of the liquid. Generally, to correct this problem must be passed either by a replacement of the impact part or by a break-in or chrome-plating phase to reload.
Wear of the joints: at each end of the rod and the cylinder, some cylinders are dedicated to sealing the assembly. They tend to wear out over time. It is then necessary to replace them to allow them to play their role again. Their replacement is not a very complicated step. Still, it requires a minimum of tools to achieve it in the right conditions and reinject the liquid under pressure in the hydraulic cylinder.
Things You’ll Need
- Oil Plug
- Jack Hydraulic Oil
1. Examine the oil filler cap to make sure it is in place and good condition if an oil leak is discovered. If it is missing, Sears has spare parts that can be ordered. The plug of the current 3-ton service jack model 875.501390, for example, is 950139-06.
2. Replace the oil by releasing the valve gear assembly and removing the plug. Next, turn the plug so that the fat drains from the well. Refill the oil and replace the cap. Do not use hydraulic brake fluid, alcohol, motor oil, oil, or dirt. Next, open the purge valve to remove air in the hydraulic chamber. Pump the cat handle a couple of times and then release.
3. Lubricate all moving parts and replace corroding parts if filtration continues. The ram and the plunger pump are susceptible to rust.
4. Open the discharge valve completely, but very slowly, when you want to get off the chair. Turn counterclockwise. Opening the lid allows the oil to flow back into the tank. This releases the hydraulic pressure in the cylinder.