Hello All - an update to this saga. Seems that the owner of the engine had the wrong tooth count on the two missing gears. His initial numbers were 9 T on the lower
gear and 6 T on the upper. Actually, they are 12 T and 8 T. I got there by just playing combinations. Then we had some bad...
Hello All - I just got off the phone with the owner and he is going to send me the Cam Shaft gear for me to measure. He is also going to remove the cast housing that surrounds the Cam Shaft gear and the pinion that drives it and carefully measure the Center distance for that pair. Having that...
Occupant - using 7 DP I got a PD for the 12 T pinion on the Crankshaft of 2.816 which is quite a bit larger than the measured OD dimension. This was using Helix angles of n 52.5 and N 37.5; the center distance calculated to 2.219 in. which is certainly close enuf.
Bob Price
A*G*M
WOW - so maybe all of this is so hard because the gears really are 7DP and not 8?
The owner is a retired machinist and it is hard to believe that he could have used and 8 DP gauge to measure 7 DP gears and not noticed something wrong. Guess I need to talk to him about this.
Thanks Occupant...
Good Morning - I looked at using 3/8 Circular Pitch and could not seem to get a combination that worked without getting a very large diameter 12 T Pinion. As for the Crankshaft gear being 7 DP, I just checked with the folks at Ash Gear and they do have a 7 DP hob but doesn't that beg the...
Hello again Gearcutter - as I tried to explain, the helix angles of the existing gears are not accurately known since they are still on the engine. The teeth were measured with a new set of 14.5 Deg. PA gear tooth gauges and also, I am assuming that the PA is 14.5 because the gears were made in...
Hello Terry - I knew all that stuff going in; what I didn't appreciate is the extreme Helix Angles needed to make the gears work. See the attached copy of my calculations to see what they turned out to be for the gear set on the Crankshaft. I have yet to do the Camshaft set but expect to get a...
Hello Terry - all that is good info but my view is that we have two of the four gears and we know the numbers of teeth in the missing gears and we know the Pitch and the Pressure angle. Plus, there are two cast housings that surround the mating gear that meshes with the Crankshaft gear and a...
Good Morning Tbuelna - thanks for the response
This project is restoration with the intent of running the engine at antique marine engine shows. Probably won't see more than 25 hours use per year. As I mentioned, the gears are 14.5 deg. PA and 8 DP which would be typical for that era. Just...
Hi Gearcutter - as you will note from the dimension sketch, all the information came from the guy with the engine: he is in Tennessee and I am in NY. He measured the teeth with some gauges and got the OD of the two existing gears with a caliper since both existing gears have even numbers of...
I am trying to reverse engineer some missing gears on a 1900 era antique marine engine. Two of the four gears that drive the camshaft from the crankshaft are missing. I have a cartoon of the AS-MEASURED dimensions of the crankshaft gear and the gear on the end of the Cam Shaft attached. I know...
Another picture - it shows a crack that started at the outside edge of the fillet weld and went out into the 1.50 in. thick palm plate. I was told the the steel conforms to American Bureau of Ships specification which calls for a minimum of 440N/mm^2 ~66,700 psi. I have no idea if the palm...
Hi Guys and thanks for all the suggestions. The Margot rudder is NOT a cantilever since it is supported by the end bearing which is part of the massive skeg which I think you can see in one of my pictures. Secondly, the pintle shaft in NOT a tube but a 7 in. diam steel bar so it is stiff. Third...
Hello 3DDave - the rudder is hydraulically controlled with a single cylinder and there are double limit switches at the stops.
Theoretically, the torque was shared by a half round key that mated with a slot in the lower palm plate but that was really useless. So yes, the torque was taken by...
Hello desertfox and thanks for your comments -
My conclusion about the welds is based on my assumption of a value for the water pressure on the rudder which worked out to be approx. 200,000 lb-in of torque on the welded joint. I then designed a joint that had a SF of 5 which was drastically...
Here are some JPG pictures of the failed parts. The square plates are the upper palm plate to which was welded the stub shaft. You can clearly see the very small fillet weld that was between the OD of the stub shaft and the plate and the view of the end of the shaft which was welded to the ID...
I'll take this in pieces - dhenger > I'll process some photos later this morning and you will see how "weedy" things were.
LittleInch - the tube [pintle shaft] is a piece of 8 in. Sch. 80 pipe to which, both blades are welded plus of course, the ribs. The extra plates on the aft end of the...
Thanks Mike - the existing welds failed because the design was grossly undersized and poorly executed. In order to design what is needed, knowing the potential torque requires knowing the water pressure on the rudder. Once one knows that, one needs to allow for the fact that the rudder is...
