[modeleng] Re: Track circuiting & Loctite

Hi John

Very interesting!  From this, I deduce that:

1) Loctite is an effective insulator.
2) Most Loctite joints have metal-to-metal contact in them somewhere, as the 
joint gap is never perfectly maintained.

The ability of Loctite-built trains to operate track circuits therefore 
seems to be more a matter of luck than judgement!

If  anyone else has done any tests, I'd be interested to hear the results.

Regards
Ron

----- Original Message ----- 
From: "John Pagett" <john_pagett@xxxxxxxxxxxxxxxx>
To: <modeleng@xxxxxxxxxxxxx>
Sent: Saturday, November 26, 2005 1:20 PM
Subject: [modeleng] Re: Track circuiting & Loctite


> 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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