Reply To: Ex Air ministry Alcon Pumps

[sidevalve5]

Hi David,

Have a 1½” Alcon pump powered by the Villiers engine. Got it in the 1980’s and used it for irrigation. But then got sprinker rotor heads that needed a higher pressure (30 – 35 psi) than my original ones. The pump also started to take an age to prime. Fitted a new seal kit I got from Vulcan Water Pump Seals, it improved the suction, but still the pressure was not sufficient. Got another Honda engined Clark pump (26 meter head), but still the pressure was not enough. So did try to link the two together, but I only got a small increase in pressure. In the end got a Robin engine Koshin pump (30+ meter head), it performed well.

Took the Alcon pump apart again and found the engine crankshaft was pitted with rust. I think these indents allow a small amount of air to get past the seal and effect the pump’s performance. I was going to go along a similar line to yourself and sleeve the crankshaft. But without your skills I was going to use a hardened stainless steel shaft repair sleeve. Proposed to fit it over the shaft then grind off the flange. What do you think of that idea.

Decided I would swap the Koshin pump and fit it on the nearly new Honda engine, the Clark pump onto the well used Robin engine. Found that the crankshaft on the Robin engine had grooves on it where the seal was in contact with it. Also the Clark pump seal was not in the best condition, so replaced it with one from Vulcan. Now have two pumps that perform well, although the Koshin is the superior one.

Dropped on some Evenshower Oscillating Spraylines and these operate at a much reduced pressure. In fact I now use the Clark pump and only need half revs from the Robin engine. The original pendulum operated oscillation valve was worn out and leaked everywhere. So make another from a pair of ¼” ballvalves. But the operation was too stiff for the pendulum, freeing them up caused leaks. Have just spent Easter Sunday making a new valve with a 3 port L configuration. Have high hopes of success and will be starting irrigation this week. It needs it too, in my part of the world near Evesham we have not have any significant rain for 6 weeks or more. Am going to put a pressure gauge on the irrigation system to see exactly what pressure the spraylines need. They are very satisfying to see operating, gently and quietly going from one side to the other in true 1950 – 60’s market gardening style.

Best wishes,

Grahame