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Point rodding fishplate nuts

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Point rodding fishplate nuts

Unread postby David Holden » Wed Apr 6, 2016 3:18 pm

Basically which way round should these be fitted, chamfer down against the rodding or flat side down.
I've heard theories for both ways, chamfer down doesn't damage the galvanising.
Flat side down grips better and the chamfer is to promote water dispersal!

There must be chapter and verse some where.
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Re: Point rodding fishplate nuts

Unread postby Richard Pike » Wed Apr 6, 2016 6:30 pm

BRS-SM 201 says it all for me. Anything else simply will not do.
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Re: Point rodding fishplate nuts

Unread postby David Holden » Fri Apr 8, 2016 6:31 am

Thank you Richard.

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Re: Point rodding fishplate nuts

Unread postby John Webb » Fri Apr 8, 2016 9:41 am

Not having, as yet, handled any point rodding, is there any reason why there is not a washer between the nut and the top surface of the point rodding? Only that would protect the galvanising from the turning nut when tightening things.

Out of curiosity, have there been many instances of the nuts/bolts working loose and the bolts dropping out? Or is there a regular maintenance schedule that is followed to minimise this happening?
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Re: Point rodding fishplate nuts

Unread postby Richard Pike » Fri Apr 8, 2016 10:15 am

A close study of the drawing shows a disparity in the shape of the fishplate and the internal dimensions of the rodding itself. The rodding 'nips' onto the fishplate. The shear force on the rodding 'T' bolts should be near negligible. All the force on the bolts should be in tension. If the nut is reversed with the small mating surface touching the rodding the bolts are overstressed when tightened by hand tools. The large flat surface will give the required torque for the poor liitle half inch Whitworth thread. The small surface of the nut the wrong way up creates a mechanical advantage that is not intended.
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Re: Point rodding fishplate nuts

Unread postby scarpa » Fri Apr 8, 2016 10:10 pm

The reason the nuts have chamfered edges originally a Tee spanner was employed to undo the nuts and it was discovered when undoing the nuts they would become stuck in the tee spanner.by chamfering the nuts this was preventing the nuts becoming stuck.
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Re: Point rodding fishplate nuts

Unread postby Mark Lamb » Sat Apr 9, 2016 6:05 pm

In response to the question: "Out of curiosity, have there been many instances of the nuts/bolts working loose and the bolts dropping out? Or is there a regular maintenance schedule that is followed to minimise this happening?"

From my time as a Linesman (now Mtce Tech, I suppose) odd ones used to work loose from time to time. There was a schedule, but it very helpfully (!) required us to check all bolts and nuts for security every visit, which was usually once a month. Of course this was virtually impossible to physically do, especially on a mechanical district with acres of rodding!

The trick was to ensure all nuts were squared off parallel to the rodding on installation. That way you could see if one was turning by not being square.

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Re: Point rodding fishplate nuts

Unread postby John Webb » Sun Apr 10, 2016 7:49 am

Mark Lamb wrote:In response to the question: "Out of curiosity, have there been many instances of the nuts/bolts working loose and the bolts dropping out? Or is there a regular maintenance schedule that is followed to minimise this happening?"

From my time as a Linesman (now Mtce Tech, I suppose) odd ones used to work loose from time to time. There was a schedule, but it very helpfully (!) required us to check all bolts and nuts for security every visit, which was usually once a month. Of course this was virtually impossible to physically do, especially on a mechanical district with acres of rodding!

The trick was to ensure all nuts were squared off parallel to the rodding on installation. That way you could see if one was turning by not being square.

Mark

Thanks for that insight, although our rodding run, when installed, will be a fairly short run due to lack of space!
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Re: Point rodding fishplate nuts

Unread postby Fast Line Floyd » Sun Apr 10, 2016 4:33 pm

We've discussed this elsewhere but the LM always put the chamfered edge down onto the rodding (with no washer) so as not to scrape away the galvanising on the rodding, and once done up tight the bolt heads were hit with a hammer to lock the nuts on (because the bolts are malleable it is still possible to undo them with a little force).

I worked a number of boxes on the LM and never remember a bolt dropping out or the bolts ever being tightened.
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Re: Point rodding fishplate nuts

Unread postby Mike Hodgson » Sun Apr 10, 2016 6:30 pm

Wouldn't the clout with a hammer damage the galvanising anyway?
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Re: Point rodding fishplate nuts

Unread postby S&TEngineer » Sun Apr 10, 2016 7:39 pm

When I was a trainee in the signal gang (long time ago now) we never hit the nuts or bolts with a hammer. Once the nuts were tightend with the T spanner you hit the rodding with the hammer to force the fishplate into the rodding and then tightend the nuts again leaving them square on to the rodding so that you could visually check at a later date if they were working loose. Like Graham I have never known nuts to work loose to the point where the rodding becomes slack.
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Re: Point rodding fishplate nuts

Unread postby Richard Pike » Sun Apr 10, 2016 8:31 pm

Putting the nuts on upside down can cause the rodding to develop a 'dish' below the nut. I feel this dish releases some of the sideways 'nipping' pressure the rodding has on the fishplate.
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