[modeleng] Re: Track circuiting & Loctite
- From: "John Pagett" <john_pagett@xxxxxxxxxxxxxxxx>
- To: <modeleng@xxxxxxxxxxxxx>
- Date: Sat, 26 Nov 2005 13:20:53 -0000
Ron,
Here are the results of my resistance measurements:-
Where possible I've allowed for meter lead resistance. Locomotive brakes
were wound well off. Coupling rods were left on!
5" Metro 2-4-0T - not built by myself so I can't comment on costruction
methods. Measured on complete loco.
Leading wheelset 0.1 Ohm
Driving wheelset (crank axle, pinned) 0.1/0.2 Ohm
Trailing coupled wheelset 0.0 Ohm
5" Sweet Pea 0-4-2 - Measured on rolling chassis. Wheels are loctited and
the driving and coupled wheels are also located by a 4BA socket grub screw
tapped into the interface between the wheel and the axle.
Leading coupled wheelset 0.1/0.2 Ohm
Driving wheelset 0.0/0.1 Ohm
Trailing pony - this is where it gets interesting - 60 to 200 Ohms. This
resistance is all in the interface between one wheel and the axle, and I
couldn't get a steady reading. I wonder if I should investigate this a
little closer?
4 wheel driving truck. Wheels are loctited to axles, no pins and there are
no alternative paths for the current - ball races sit in tufnol housings and
brakes are cycle blocks.
Leading wheelset 0.0 Ohm
Trailing wheelset 0.0 Ohm
Old wheelsets from Bromsgrove SME passenger cars - not fitted to anything at
the moment. Wheels are loctited on but since I didn't make them I've no idea
of the clearances involved.
Wheelset 13 0.2/0.3 Ohm
Wheelset 16 13.8 Ohms
1st unmarked wheelset 4.4 Ohms
2nd unmarked wheelset 4.65 k Ohms (Yup, 4650 Ohms)
3rd unmarked wheelset 160 Ohms
I suspect that what this tells us is that loctited wheels may be
satisfactory for track circuiting ( and they work fine for us in practice ),
but to be really certain may require care in fitting and pins on the
interface.
Hope this helps (he said, muddying the waters!!)
Cheers,
JohnP
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