I'm sure there is an expert opinion from somebody on the site.*
But in as few words as possible, A rubber impeller pump creates a significant amount of lift that raising the water several feet above its source, before it reaches the pump impeller, without being primed first.* It's the best pump for our application of drawing raw water into our engines cooling system that is usually above water level.
Gear pumps and rotary vain (slinger) pumps have very little lift capability and must be bathed in or have the liquid (water) very close to the pump intake.
Gear pumps are great for some applications, like moving fairly high viscosity liquids between containers. Rotary pumps can pump very hot liquids, like your engines internal coolant, without damage.* In agriculture, rotary vain pumps for years can reliably take a low pressure water source and pressurize it to much higher levels and spray it through a nozzle to water fields or spray insecticides on crops.
They all have their purposes and this just happens to be the best type of pump for our circumstances. The downside is the impeller rubs against the cam block and pump housing to create the lift and which also causes it to wear out.
-- Edited by Edelweiss on Monday 15th of August 2011 04:48:42 PM