I'm having a little bit of trouble with a rolling jack, maybe someone can offer me some insight...
Equipment: Rotary Lift brand 7,000# rolling jack [pneumatic over hydraulic scissor jack mounted on a trolley which rolls between the rails of an alignment ramp of the same brand]; 7 years old, 5.5 years in moderate service. Specs Dexron III fluid, am using Mobil Dexron IIIh at the moment.
Background: The old adage of "never buy an automobile from a mechanic" applies here. Maintenance requirements ask that the hydraulic oil be check twice a year. After never finding it low I forgot to check it for about two years. It has always accumulated oil on top of the pump around the exhaust, but I attributed it to a faulty filter/drier/oiler oiling too much.
In December it started running quieter and erratically, but that wasn't enough to get me to check the oil. When I finally checked the oil it was almost a quart low and too late, the piston return spring [compression] had broken. The spring isn't available to purchase.
Rotary Lift treats the pump as a part that should be changed as a unit or sent in for repair. The pump costs $925 US + shipping + tariff + 16% sales tax. Grainger has a similar Taiwanese pump for $11,200 pesos delivered, still way too much. I would rather not send it out to be repaired; I imagine whoever does it as being equally incompetent as myself and me eating it on the shipping, and still have a semi-functioning pump.
A friend took the spring to a machine shop in Puebla that makes springs, but instead of having it made he brought back five similar springs that look like ones they made which came out defective. I installed the spring which was the closest match. It works, but it would seem the spring is too weak, possibly causing quiet erratic operation. Another spring he brought feels stronger than the original, I will try it next if this one doesn't work.
The problem I am having now: I suspect the quiet/erratic operation is caused by air trapped in the system. It doesn't want to lift until it hits the chassis of the auto it is lifting. Once it makes contact it lifts well, but somewhat erratic. It was behaving in the same manner in December after running low on oil as well.
What I have found to work best to bleed it is: Lower it completely; crack hose fitting at pump; start pump; once fluid comes steadily out of the fitting I tighten it. The jack lifts even when air or fluid is leaking out of the fitting. The hydraulic cylinder is mounted diagonally, with the inlet fitting below the pump, which I suspect is compounding the problem. I have not found any bleeder [I'm not familiar with hydraulic systems other than brakes].
My final two ideas are to use my same bleeding procedure, but while lifting an auto; or to dismount the pump and place it lower than the cylinder and bleed from the hose fitting at the cylinder.
Maybe someone has experience with this type of hydraulics and could offer me some advice?
Equipment: Rotary Lift brand 7,000# rolling jack [pneumatic over hydraulic scissor jack mounted on a trolley which rolls between the rails of an alignment ramp of the same brand]; 7 years old, 5.5 years in moderate service. Specs Dexron III fluid, am using Mobil Dexron IIIh at the moment.
Background: The old adage of "never buy an automobile from a mechanic" applies here. Maintenance requirements ask that the hydraulic oil be check twice a year. After never finding it low I forgot to check it for about two years. It has always accumulated oil on top of the pump around the exhaust, but I attributed it to a faulty filter/drier/oiler oiling too much.
In December it started running quieter and erratically, but that wasn't enough to get me to check the oil. When I finally checked the oil it was almost a quart low and too late, the piston return spring [compression] had broken. The spring isn't available to purchase.
Rotary Lift treats the pump as a part that should be changed as a unit or sent in for repair. The pump costs $925 US + shipping + tariff + 16% sales tax. Grainger has a similar Taiwanese pump for $11,200 pesos delivered, still way too much. I would rather not send it out to be repaired; I imagine whoever does it as being equally incompetent as myself and me eating it on the shipping, and still have a semi-functioning pump.
A friend took the spring to a machine shop in Puebla that makes springs, but instead of having it made he brought back five similar springs that look like ones they made which came out defective. I installed the spring which was the closest match. It works, but it would seem the spring is too weak, possibly causing quiet erratic operation. Another spring he brought feels stronger than the original, I will try it next if this one doesn't work.
The problem I am having now: I suspect the quiet/erratic operation is caused by air trapped in the system. It doesn't want to lift until it hits the chassis of the auto it is lifting. Once it makes contact it lifts well, but somewhat erratic. It was behaving in the same manner in December after running low on oil as well.
What I have found to work best to bleed it is: Lower it completely; crack hose fitting at pump; start pump; once fluid comes steadily out of the fitting I tighten it. The jack lifts even when air or fluid is leaking out of the fitting. The hydraulic cylinder is mounted diagonally, with the inlet fitting below the pump, which I suspect is compounding the problem. I have not found any bleeder [I'm not familiar with hydraulic systems other than brakes].
My final two ideas are to use my same bleeding procedure, but while lifting an auto; or to dismount the pump and place it lower than the cylinder and bleed from the hose fitting at the cylinder.
Maybe someone has experience with this type of hydraulics and could offer me some advice?
