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PUMP DRIVE MECHANISM

The piston stub axle is welded to a pushrod made of 40 x 40mm mild steel rectangular hollow section. This pushrod connects the piston to the trolley axle, which is 1300 mm away. As mentioned above, if high heads are to be used then a 2 inch PVC pump barrel should be used, and then at least part of this pushrod should be replaced say by 1 inch GSP steel pipe, to avoid running against the rear steel flange which clamps the PVC barrel.

Pressed on the machined ends of the trolley axle are 2 double-rubber-sealed ball bearings, which run directly on 2 guide rails of 30 x 30mm mild steel angle section. These 2 guide rails are welded to the main frame of the machine. On to the pushrod and trolley axle assembly is welded a framework for the 2 timber seats, back to back along the machine axis. Two fixed footrests are an integral part of the machine frame, but of course adjustable timber or steel footrests can or should be fitted if required to cope for varying heights of operator, and to increase operator efficiency and comfort.

To pump water, 2 people sit back to back on the timber seats and push alternately against their footrests, thus moving themselves, the trolley and the pump piston through a stroke of up to 700 mm.

ADDENDUM 1999:

1. Note that the Trolley concept can be easily extended to a four-man or 4-person system, with 2 persons side by side back to back with another 2 persons side by side. Also the trolley system can easily be adapted to power traditional mortar-and-pestle milling by using a rope and 2 pulleys (the mortar and pestle unit itself would still require one operator for guidance, who would not however need to make any physical exertion). It should also be possible to link a 4, 6, 8 or more person trolley system to a crank and flywheel for powering other devices such as a grain thresher or alternator or dynamo for battery charging or direct powering of electrical devices. This last concept of course competes with the more traditional 4-person dynapod as shown in one of the accompanying drawings with the centrifugal water pump.

2. Note that it should be possible to design a system which can easily be changed between 3 inch, 4 inch and 2 inch pump barrels, and also with varying valve sizes (valves should anyway always be easily changed for maintenance, cleaning or replacement).

3. Note that it should be simple to design a pump of this type which can be used with a trolley mechanism or with a pedal mechanism. That would require some minor changes only to the design as shown here.

PUMP PERFORMANCE......................................................................Pump110.htm

DRIVE MECHANISM COMPARISON..............................................Pump120.htm

PRODUCTION COSTS........................................................................Pump130.htm

OPERATIONAL COSTINGS...............................................................Pump140.htm

SUMMARY AND CONCLUSIONS....................................................Pump150.htm

REFERENCES......................................................................................Pump160.htm

APPENDIX........................................................................................... Pump170.htm

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