Congrats to Minh-thanh . I noticed that he has some new credentials on the forum! He, like all of you, make this, most importantly, a fun place.
I see how the ETW pump works, but is it really a pump, or just a variable metering valve for pressurized oil?
Agreed, it is pretty straightforward.
4 is fixed, the brass knurled bit on my version. It has an angled surface to match one on the drive gear which causes the piston 6 to reciprocate. The phasing of this to the flat on the bottom of the piston controls the flow rate. Easy to adjust down to small flows and no valves to stick/block.Roger,
OK, now I see it better. The worm gear rotates the shaft item 6 at a speed proportional to the engine speed. The handle item 4 oscillates back and forth to move the piston (also item 6) up and down in sync with the opening and closing of the in and out ports in item 1. Adjusting the angular range of item 4 can also change the pump stroke volume. Similar to a diesel injector.
Got it! Thx
Hi Steam,Hi, Post #63. Thanks, as it explains the "non-crankcase" feed of combustion air. So really, unlike crankcase fed motorcycle engines, there is very little lube oil going to get into the combustion chamber. And I now appreciate why a feed and return arrangement for crank bearings is a practical alternative to "total loss" lubrication.
I have seen "ships' engines" with blowers that are 2 strokes and have side ports in the cylinder for either exhaust or inlet. - I think it depends on whether it is a "huge" slow-speed engine or "small high-speed" engine as to which way it is configured?
I think this is technically called 'edge loading'. It's a major factor for needle roller bearings too. Broadly speaking the longer the bearing is in relation to its diameter the stiffer the shaft has to be in order to avoid issues.One significant cause of models wearing bearings is shaft flexure. A major issue on full-sized cranks and related bearing wear. The parallel idea is the reason many motorcycle engines use a ball bearing on the drive end, and either roller bearing or bronze bush on the timing side where there is no side thrust. But if the crank is not stuff enough the bronze bush wears at high speeds when the crank flexes and effectively is not parallel with the bearing so touches ends and causes wear. Aeroplane and boat engines with propellers do not have the side thrust of belt or chain drive on a cantilever end of crank professing beyond the bearing, so can tolerate a bush for longer Without wear.
There will definitely be some bronze bearings in this model, but maybe some ball and roller, too.I have to agree with using bronze bearings I YHINK if you look up load ratings you will find a full cylindrical bronze bearing with oil lube will problem out last the engine. There is a specific bronze bearing material number but it escapes me. Full floating automotive steel connecting rods often have bronze bearings even heavy duty diesel Even with minimum oil they they are like the ever ready rabbit .