Pumps of this type were used in car engines along with a couple of other types and usually driven off of the distributor drive. I suspect that this is very old technology now and most, if not all, current engines have pumps fitted around the crankshaft at the auxiliary drive end are often of the crescent type. Google types of oil pump and have a look at the images to see a load of types.

Clearances on this type of pump are fairly tight in order for the pump to be efficient….so you need to ensure the gears mate well and there's the minimum of clearance for the pump body cover plate….

Austin Seven (not Mini) engines have this type of pump.The handbooks state that the oil pressure should be 1 or more PSI. A reasonable engine with the correct 30 grade oil usually reads 5 PSI when warm.

Brian

The gears need to have some backlash. Rolls Royce Oil Engine Division found that having too close a fit produced short term pressure spikes, (circa 600 psi with a gauge reading of 60 psi ). The result was that external steel oil pipes were splitting.

You could hear the pipes "ring" above the noise of the engine running! The spikes were quite visible on an oscilloscope trace of the signal from a pressure transducer.

The problem seemed to stem from oil being compressed in the space between Tooth crest and the corresponding Tooth root. Increasing clearances by a few thou reduced the spikes to an acceptable level.

To minimise leakage, the gears should be close fit in the casing, (minimal endfloat, circa 0.002" ).

Howard

Presumably the fluid flow is round the outside of the gears not between the meshing teeth? I can see that there would be a lot of pressure between the teeth, tending to infinity as the fit becomes perfect.

Or to put it infinitely more simply : Yes the fluid goes around the outside of the gears, being displaced out through the outlet port when the gears mesh together.

Yes leakage across the teeth is generally considered less of a problem than leakage across the faces of the gears when the end covers get worn over the years. Leakage out around the drive spindle can also be a problem if no seal is fitted. These pumps, being positive displacement, will actually pump at quite high pressures. Typical oil pressure in an older motorcycle engine with a gear type oil pump and plain shell bearings could be 60psi and upward.

This is the third time I've typed this reply, forgotten how un-user friendly this web page is. Anyway it's a standard machine tool coolant pump made in their thousands by companies world wide over the years. Below is a pic of the similar thing in the guts of an original Bulleid pacific. Part of a double pump, two sets of gears on the same shaft. Not for forward and backward but one to pump to each side of the oil bath via a filter each side. Both feeds join in the middle and feed a spray bar going the length of the oil bath. Pumps in forward or reverse by a clever arrangement of non return poppet valves cast in to the pump body. Made by Hamworthy Engineering of Poole and originally designed for reversible marine diesel engines IMHO, although I have never seen this written anywhere.

Its made by Whitney (City Road) of london. Nice little thing, ive got one too. Works very well. Early 20th C, the premises on City Road in Islington were destroyed in the Blitz. Its now the site of the huge Old Street roundabout. Do a goodle search for whitney city road and in about 5 minutes youll be an expert on them, as there isnt that much known…

i collect Whitney steam engines and accessories, if you ever want to pass it on to someone else then let me know ;c)

cheers!

rich

ps this is my first post- hello everyone!

Mines currently being the condenser pump on my latest steam launch build. Seems to work. It’s driven via meccano gears from the crankshaft.

whitney engines are lovely. I’ve got a small vertical in the ‘house colours’ of maroon and a large bottle shaped vertical with reversing gear, a few steam pumps and a few hand pumps. They are mostly maroon, apart from the bottle engine(polished) and the gear pump (same green as yours), but they are all absolutely beautifully built.

They also did kits and casting sets, my large hand pump and bottle engine were both kits I think.

ill post some pics at some point, because there aren’t enough pics of them on the web…

cheers!

rich