Diagnosing and repairing a new commercial lubricator
|Steve Addy||31/08/2018 11:51:39|
|88 forum posts|
At the beginning of July this year I purchased a 3.5" gauge Garratt, based on the Darjeeling and Himalayan one of 1910. The loco has been designed and built by a fellow club member Jack Evans and is two 0-4-0 bogies based on Simplex with a mighty boiler slung between them.
The loco is fitted with two commercial oscillating lubricators, one at each end, the front one refused to work, but it was impossible to see if it was even going round given the length of the machine.
I fitted a couple of priming hand wheels, removed the excessive end float in the cranks and tidied up the raggy looking pawl which imparts the motion to the ratchet. At this point the pump felt like it was working when turned over by hand and did now visibly rotate when the loco was running - still no oil delivery
I dismantle the offending device and measured then drew the porting in CAD to see it that was the problem - no, it was fine. If the pump was turned over by hand without the bottom clack valve it would pump motor oil. If the clack spring was reintroduced with a bit of load on the ball, the pumping stopped and the pump made a very strange noise best described as a squirting sound.
It turned out that the cylinder pivot was not perpendicular to the portface, preventing it sealing. This was the source of the squirting noise and the reason it felt as if it was working - it was pumping, just not out of the delivery.
To cure it I silver soldered a plug in the cylinder pivot hole, then set the cylinder up on parallels in a large machine vice. The hole was drilled and tapped using a drill press to keep things square and the vice was transferred to the surface grinder for a little whistle up.
On reassembly the pump finally behaves like it should.
This might save someone wasting hours like I did wondering what on earth was wrong with it.
|Steve Addy||31/08/2018 12:06:11|
|88 forum posts|
Here she is on the turntable at Derby SMEE, Morley. A big engine for a 3.5" gauge, over five feet long.
Edited By Steve Addy on 31/08/2018 12:07:13
3396 forum posts
What a beauty she is too! Thanks for posting the pic. I used to watch the full-sized later model Garratts shunting in and out of the yard at the powerstation I worked on in Zimbabwe circa 1980. Beautiful machines to see in motion, as I am sure yours is too.
|Steve Addy||24/12/2018 14:54:35|
|88 forum posts|
Further to this lubricator saga.
After the thing worked for a couple of running sessions at Morley it again stopped going round. I found the raggy pawl I had tidied up must have been case hardened as it had lost the business end. I made a new one from gauge plate which is through hardened and pumping is restored. Both front and rear lubricators go through the oil at the same rate now and the loco appears to steam better due to less being wasted overcoming friction.
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