Gray Marine diesel engines of WW II

Last crawled date: 1 year, 11 months ago

The Gray Marine series of 6 cylinder 426 cu in engines of WW II
Detroit Diesel, a division of GM, introduced the 71 series of diesel engines in 1938, 71 cu in per cylinder.
The original models were 2, 3, 4 and 6 cyl engines, intended for a wide variety of applications. They were two stroke diesels inline with an overhead cam driving exhaust valves and injectors and a perforated cylinder sleeve for intake. The camshaft, balancer shaft, blower and connected pumps were all driven by a gear train behind the block. The 71 series was produced until 1998.
Late in 1941, with war looming on the US, Gray Marine was tasked with adapting the 6-71 engine for naval use. This conversion entailed providing for sea water cooling, which included a separate pump, heat exchanger for fresh water internal cooling of the engine and sea water cooling of the exhaust manifold.
In an early model (64HN5) a Borg-Warner transmission was used that was also cooled with sea water. This feature was dropped in all subsequent transmissions used, which were made by Twin Disc. Generators and Starters were manufactured by Delco-Remy.
The blocks, cylinder heads, crankshafts, camshafts, valves, injectors and associated mechanisms as well as the gear train, blowers and governors were directly produced by Detroit Diesel and identical to those in the 6-71 engines; records show that about 100,000 of these engines were produced during WW II, including the Gray Marine adaptations.
The 64HN9 engine was used in nearly all 36 foot landing craft, lncluding LCP(L)'s, LCP(R)'s, LCV's and LCVP's. Early examples of them used the earlier 64HN5, which included the sea water cooled transmission mentioned. The 64HN9 and 65HN9 (CCW version) were used together in LCM's and LCC's
Two 64YTL's and a 65YTL (CCW) were used in all LCT's
Eight straight DD 6-71's were used in the LCI(L), four driving each propeller.
Main differences among models were the transmissions and peripherals.

The models
I am showing two of the models in the series to highlight the differences. They were built in SolidWorks with many parts having multiple bodies to minimize duplicate references. Each engine consists of about 4,500 parts. I ommitted modelling most washers (about 500 of them) and most bolts and nuts are reduced to the simplest form possible.
The body colors, except where painted, reflect the materials the parts were made of. The scale drawings show the complete models. The mechanism is a separate model that includes all the moving parts of the engine functionally, that is, theoretically it could be animated to show the motion. The models, which include four other variants not shown, are about 22 GB. I have also uploaded the ttf font I created to label my projects with.
See also:
https://grabcad.com/library/lcc-mk-2
https://grabcad.com/library/landing-craft-tank-mark-5-1
https://grabcad.com/library/landing-craft-infantry-pt-1-1
https://grabcad.com/library/landing-craft-infantry-pt-2-1
https://grabcad.com/library/landing-craft-infantry-pt-3-1