HYDRAULIC ELEVATION SYSTEM DETAILS

The dish elevation control system is hydraulic. The current configuration of my hydrauilc system, shown in the diagram below, is an implementation of suggestions from Joe K1RQG and improves substantially the performance of the elevation control system compared with the previous "no-accumulator" configuration. In particular, the new configuration uses a hydraulic accumulator and pressure switch arrangement to determine when the electric-motor-driven pump runs. With the accumulator/pressure switch arrangement the hydraulic pump comes on only when the system pressure drops below 1050 psi, repressurizing the system to 1150 psi, as opposed to the previous system configuration that turned the electric motor and hydraulic pump on and off for each and every commanded movement in elevation. This current configuration dramatically reduces the number of times the motor/hydraulic pump is turned on and off in a given period of time, thereby reducing the operational stress on the motor and pump, and it also results in smoother overall operation of the elevation control. After now having experience with both non-accumulator and accumulator hydraulic control systems for my dish I can say with certainty that the accumulator/pressure switch configuration is a superior configuration. It is my strong opinion that anyone considering using hydraulics for elevation control of their dish should plan from the outset to use an accumulator/pressure switch configuration to determine when the motor/pump runs. The minimal additional expense relative to a no-accumulator system is well worth it in terms of improved operational smoothness and reduced stress on the motor and hydraulic pump. K1RQG has prepared a PowerPoint presentation describing his hydraulic system; he has posted his presentation at http://www.qsl.net/k1rqg/K1RQG%20HYDRAULIC%20SYS_files/frame.htm.

The diagram below shows schematically the details of my hydraulic system configuration.

Below: Photograph of the tower-mounted hydraulic system components with several of the important components identified and labeled.

For reference, the major components comprising this particular hydraulic system are:

Hydraulic Cylinder: Prince 4" bore x 16" stroke, 1-3/4" shaft, www.surpluscenter.com P/N 9-1172-16-S

Hydraulic power pack: 220VAC, 1 hp, ~1.5-gal reservoir, www.northerntool.com, P/N 105871

4-way valve: 120VAC solenoid valve, closed center, www.surpluscenter.com P/N 9-7237 (uses D03 sub-plate P/N 9-4070-1)

Flow-control valves: 2 ea., 1/2" NPT, www.surpluscenter.com P/N 9-502-50

Pressure gauge: glycerin-filled, 0-2000 psi, 1/4" NPT, www.surpluscenter P/N 21-1246-J

Check valve: 1/2" NPT, 2000 psi, www.surpluscenter P/N 9-1019-50

Pressure switch: SPDT, NEMA4, 3000 psi max, set to 1100 psi, www1.mscDirect.com P/N 56491152

Accumulator: 45 cu. in., 3600 psi, diaphram-type, www1.mscDirect.com P/N 76133990 (charged to 750 psi argon or nitrogen for 1100 psi fluid operations)

It is expected that the specific components that are appropriate for other installations may be different from those listed here, depending upon the particular physical characteristics of the dish system in use. Therefore, the components listed above should be considered as generically representative of what may be required in a system. Nevertheless the list may have utility for others as an example of what is a workable combination of components for this particular installation.