M-3 delivery dates

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M-3 delivery dates

Postby R36 Combine Coach » Fri Feb 09, 2018 8:00 pm

The 1988 LIRR freight carload report has the totals of M-3s delivered from Budd between 1984 and 1986 on page 9 (under "CORONA"). According to the data, 226 M-3s were delivered from Budd's Red Lion assembly plant to the Willets Point acceptance facility in 1984, followed by 34 in 1985 and 76 in 1986 for a total of 336.

This obviously includes both MNCR and LIRR units, but 142 M-3As and 174 M-3s were ordered for a total of 316. How is the final number off by 20? Also, some of MNCR's first M-3As were actually delivered in 1983. Pages 18-19 of the 2009 MNCR equipment book have the delivery/acceptance dates of the MNCR M-3As, all between early 1984 and January 1985. However no M-3s were delivered in 1983 according to LIRR.
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Re: M-3 delivery dates

Postby BuddR32 » Mon Feb 12, 2018 1:16 am

MNR got their M3As earlier, as they encountered a major problem with the cars for LIRR, related to the contact shoes, where the contact shoes on the LIRR cars would lift off the third rail around curves (if the third rail was on the outward side)

The M3 uses a General Steel 70 series truck, in which the primary suspension springs are built into the truck. The outriggers for the third rail shoe beam on the M3a is mounted to the truck frame. Because the truck frame is suspended from the axles through the suspension, there is flex, lean or give (whatever you want to call it) As the cars went around a curve, if the third rail was on the outside of the curve, the shoes on the LIRR cars would lift off the third rail. MNR didnt have this issue as the contact shoes are under-riding, and this situation actually put slightly more pressure on the shoes.

It took BUDD a while to figure out a fix, which was to mount the shoe beam outriggers to the trucks equalizer beams, which stay true to the axles and don't flex.

The M1 cars didnt have this issue, as that truck design was not sprung at all, the primary suspension springs were built into the bolster.

The M7 cars dont have the issue either, because the shoe beams are mounted directly to the end of the axles.
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Re: M-3 delivery dates

Postby DutchRailnut » Mon Feb 12, 2018 8:02 am

I hired out in febr 1984 at MN and the first M3a's were arriving during our training on Harmon.
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Re: M-3 delivery dates

Postby JamesRR » Mon Feb 12, 2018 11:13 am

BuddR32 wrote:MNR got their M3As earlier, as they encountered a major problem with the cars for LIRR, related to the contact shoes, where the contact shoes on the LIRR cars would lift off the third rail around curves (if the third rail was on the outward side)

The M3 uses a General Steel 70 series truck, in which the primary suspension springs are built into the truck. The outriggers for the third rail shoe beam on the M3a is mounted to the truck frame. Because the truck frame is suspended from the axles through the suspension, there is flex, lean or give (whatever you want to call it) As the cars went around a curve, if the third rail was on the outside of the curve, the shoes on the LIRR cars would lift off the third rail. MNR didnt have this issue as the contact shoes are under-riding, and this situation actually put slightly more pressure on the shoes.

It took BUDD a while to figure out a fix, which was to mount the shoe beam outriggers to the trucks equalizer beams, which stay true to the axles and don't flex.

The M1 cars didnt have this issue, as that truck design was not sprung at all, the primary suspension springs were built into the bolster.

The M7 cars dont have the issue either, because the shoe beams are mounted directly to the end of the axles.


Fascinating info. It's always interesting how the next generation of a car design, despite being based on the first, can introduce new problems.
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