My system consists of a Power Pack (Motor, Pump, and reservoir as one unit)
Two 40 inch hydraulic (two way) cylinders
One control valve assembly
Two flow control valves, adjustable flow in one direction, full flow the other
External check valve (Power pack has internal one, but for maintenance)
Return flow filter
Contactor to run the motor
This system can also be used to drive a hydraulic motor for azimuth control
K1RQG HYDRAULIC SYSTEM CONTROL
The complete hydraulic assembly is on a steel plate which bolts to the rotating part of
the dish mount. This is 25’ in the air and has 3 “eye” bolts attached to allow for lowering
it for major maintenance if needed.
I piped the high pressure side of my system with ½” stainless steel pipe because it was
available. You will need various adapters, reducers, plugs etc. I advise using swivel
connectors wherever you can for ease of assembly and future service.
All the hoses are locally made to length and are ¼” 5000 PSI rated. There is no need
for anything larger as we are more interested in smooth slow operation. The cost is
not much more than if ordered pre-made and makes for a much neater assembly.
The accumulator is the key item that allows for slow smooth movement. This also
minimizes the run time of the pump. During normal tracking of the moon, I have noted
that it may be 10 minutes or more between run times for the pump.
Construction Hints (cont)
The accumulator works just like a water tank on a well system. It is pre-charged to a
certain pressure with nitrogen (I chose 750 PSI) to operate the cylinders without
calling for the pump to energize at every movement request. Your data may vary due
to piston size and weight of your antenna system.
I run the pressure at 1250 PSI max and it drops to about 1000 PSI before the pump
starts and charges the accumulator back to 1250 PSI.
I use two flow control valves metered in one direction and full flow in the other for two
reasons. One is the volume of fluid required to extend the cylinder is more than you need
to retract it, and secondly, you can control for uneven weight distribution.
To my knowledge, I am the only EME station using this particular method and so far, it
has been trouble free and works excellent. I do leave power to the pump on 24/7.
I do this to maintain constant pressure and assure no air gets into the loop.
Important things to consider
The accumulator listed here is NOT the same one I have. Mine is no
longer available. There are many variations on the web page, and I
urge you to be sure that the one you order has the right capacity to
handle your project. Mine is approximately 2 quarts. I do not have
a good working knowledge, but I have been advised that one does
not need a large volume accumulator to be functional. The main
function is to maintain a relatively constant pressure and to absorb
abrupt changes when the valves are actuated.
Also, you do not need to purchase a “Power Pack”. You can assemble
your own pump, motor, and reservoir to suit your needs. The one I
have is set to bypass at 2000 PSI.
The following parts can be found at www.SurplusCenter.com
Main control valve with 24 VDC solenoids
Two plugs needed
Flow control valves 2 ea
Check valve is your choice 9-1019-50
Pressure gauge 21-1246-J
Filter is your choice (I use a fuel flow filter)
Hydraulic cylinder of your choice (I bought mine new to avoid leaks)
These parts can be found at MSC
Pressure switch 56491152
76133990 or similar. (See things to consider)
This can be ordered at www.northerntool.com
Power Pack 1530036
Rams, control box & reservoir
Motor Contactor Box