Three new inspection bolts have been made for the level check holes in the lower gear housings.
|Inspection bolt with blind axial hole and linked radial aperture|
for oil level checking
|The bolt is partly removed to check if oil comes out of the radial aperture|
|View from above|
7109 was set up for slow, heavy haulage (I'm guessing here but it will be obvious in due course); hence it will have a large gear in the lower gear case. As a result, it will not need such a deep oil bath as one set up for higher speed with a smaller gear in the same place. So the the check hole actually used will be to suit the expected oil level inside.
Going off-subject for a moment, the Teifi Valley Railway visit on 18th September 2011 revealed an interesting angle on this with the double geared Sentinel 9622 built in 1958. Have a look at the next two photos:
|Near side lower gear casing (9622)|
|Off side lower gear casing (9622)|
Also noteworthy in the 9622 photos is that bolts rather than studs/nuts are used to fix the plate in place.
Does anybody know what that big nut-like thing is in the middle of each cover plate? I guess it's a means of draining condensate from the gear case but it was so covered in green slime and it was raining hard that day so I didn't feel much like crawling about underneath and cleaning it up to find out!
A final noteworthy point: in the bottom right of the off side photo can be seen a drive chain. 9622 has double width chains whereas 7109 has single. The double chains would have been used for extra strength as, with double gearing, the drive would be only via the left or right hand chain depending on whether high or low gear was selected. 7109 has one single width chain per engine.
Back to 7109: the new gear housing bottom plates are under construction in preparation for crankcase oil to be added. Hopefully the oil will dampen the unceremonious 'clanking' heard when running on compressed air without a load.
|The bottom plate goes here|
|Definitely Crankcase oil required!|