Steam Loco(V.R) Questions.
#1
V.R.Steam Locos (and others)were/are fitted with cylinder drain cocks--to release potentially damaging incompressible water on starting the engine.
My V.R Handbook on The Locomotive (1952) also describes Cylinder Bye Pass Valves--a steam chest pressure activated semi automatic gadget to reduce cylinder air compression when drifting & make for freer coasting/drifting etc
My first question is-- Were both devices fitted simultaneously to locos?I`ve seen lots of drain cocks but don`t recall anything else under cylinders.
Second question-- The R Class as built had piston rod extensions called tailrods.These were all removed & cover plates fitted over the resulting hole in the cylinder end cover early in the life of the R`s.
Does anybody know why they were built like that & why they were removed?
Thanks,Alan.
#2
As you state, by pass valves and cylinder drain cocks serve two different purposes. The former are automatic in their operation while the latter are operated manually by the driver as necessary. By pass valves are, at the very least desirable, if not essential fittings unless their function is performed by similar apparatus such as snifting/anti-vacuum and pressure relief valves. While I'm not conversant with VR engines, I suggest they were probably situated closer to the steam chest, possibly on the side of the cylinder block, rather than beneath the cylinder adjacent to the drain cocks.

Piston tail rods were once popular because, in theory, they helped support the piston during the forward part of its stroke and also provided equal volumes in the cylinder both in front of and behind the piston. In practice, it was found that the bush in the front cylinder cover wore rapidly after a relatively short time in service and thus the tail rod soon failed to provide the intended support. Post WWII, new piston rings negated the need for additional support and the tail rods were progressively removed.
#3
(22-May-2013, 07:31 PM)Mike1 Wrote: As you state, by pass valves and cylinder drain cocks serve two different purposes. The former are automatic in their operation while the latter are operated manually by the driver as necessary. By pass valves are, at the very least desirable, if not essential fittings unless their function is performed by similar apparatus such as snifting/anti-vacuum and pressure relief valves. While I'm not conversant with VR engines, I suggest they were probably situated closer to the steam chest, possibly on the side of the cylinder block, rather than beneath the cylinder adjacent to the drain cocks.

Piston tail rods were once popular because, in theory, they helped support the piston during the forward part of its stroke and also provided equal volumes in the cylinder both in front of and behind the piston. In practice, it was found that the bush in the front cylinder cover wore rapidly after a relatively short time in service and thus the tail rod soon failed to provide the intended support. Post WWII, new piston rings negated the need for additional support and the tail rods were progressively removed.
Thanks Mike.Makes a lot of sense.--The only V.R Locos I ever encountered with snifting valves were the 2ft.6inch gauge G Class Garratts. Alan.


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