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Model Railroading > BNSF 72’ Frostline Reefer (Part 10) – Insulated Plug Doors

Date: 11/15/22 00:00
BNSF 72’ Frostline Reefer (Part 10) – Insulated Plug Doors
Author: tmotor

This is Part 10 of a series on the BNSF 72’ Frostline Reefer project.  (Parts 1 thru 9 were posted earlier.)
All Frostline Reefers have Plug Doors with insulation on the interior.  However, in an effort to decrease fuel consumption, approximately 54% of the fleet had external insulation added.  At first glance this seemed like a relatively simple exercise to add the insulation and cover it with sheet metal.  However, there is more to it than meets the eye.
Protection Scheme
The external layer of insulation is added to the upper 2/3 of the Plug Door.  The layer of sheet metal installed over it is applied before the Door Rods are installed.   There is a semi-circular “valley” formed into the sheet metal to accommodate the tubes.  The sheet metal has a rectangular section removed where the valley and horizontal ribs intersect.  (Otherwise, the layer of sheet metal would act like a shim and bring the Door Rods away from the door slightly.  This might cause the Door Rods to bind and not operate properly.)  This maintains the alignment of the Door Rods with all of the horizontal ribs.  The entire perimeter of the sheet metal has a continuous weld bead to seal it from the elements. 
The lower 1/3 of the door has the usual riveted construction.  However, on the upper 2/3 the rivets along the perimeter are absent, presumably stitch-welded instead.  (These welds are underneath the protective sheet metal, so there’s no way to see them to confirm.  But the absence of the rivets along the upper perimeter strongly implies stitch-welds.)  This hybrid approach is a bit of a head-scratcher.  Why not just stitch-weld the entire door?  Perhaps there were already pre-punched components for rivets, and they wanted to clear inventory?  A check of several other Frostline Reefers with externally insulated doors were consistent, as all lacked rivets on the upper 2/3 of their Plug Doors.  This implies it isn’t a one-off oddball, but is part of the design.
(Recently built reefers from Greenbrier have the same insulated Plug Doors, but with all stitch-welded construction; no rivets.)

Date: 11/15/22 00:00
Re: BNSF 72’ Frostline Reefer (Part 10) – Insulated Plug Door
Author: tmotor

There are Wedges that lock the door against the frame in 6 places; 2 along each side, one in the center of the top, and another in the center of the bottom.  These Wedges are driven by flat bars that are actuated by rotating the Handle.  On the standard door the flat bar is installed to run underneath the Door Rods.  However, when the insulation is added to the door, half of the flat bars needed to be relocated to run ABOVE the Door Rods.  Since these flat bars drive the Wedges that lock the door in-place, it is critical that they still function properly.  The modifications are non-trivial. 
Sync or Swim
The flat bars are all driven by the gear train (within the gearbox enclosure) under the Handle.  As the Handle is rotated, the first order of business is to pull on the flat bars to disengage the locking Wedges from the door frame.  All 6 of the locking Wedges need to be in sync and lock/unlock at the same time.  The flat bars will pull the locking Wedges toward the center of the door to unlock.  To lock the door, reverse the process and rotate the Handle in the opposite direction, which drives the Wedges into the door frame to secure it.
Detour Ahead
There are vertical flat bars coming from the top and bottom of the gearbox.  They pass thru pivot points (that change the vertical motion to horizontal motion) to drive the 4 locking Wedges along the sides.  The flat bars that drive the lower 3 locking Wedges are unchanged.  However, the flat bar to drive the upper 3 locking Wedges had to be rerouted to accommodate the insulation.
The flat bar coming out of the top of the gearbox has an offset so it can rise above the horizontal rib.  Offsets are also added to the horizonal flat bar so it can pass over the (vertical) Door Rods.  There are guides for the flat bar every foot (or so), that are welded onto the sheet metal. 
Closing the Door on YSD
All of the Frostline Reefers have Plug Doors manufactured by Youngstown Steel Door.  They wear the initials “YSD” surrounded by a rectangle, located to the right of the Handle.  Recently built reefers have identical doors, but lack the YSD initials on their doors.  I believe I know why…
YSD was sold to Global Railway in April 2004.  In spite of a $2M backlog of orders at the time of the sale, Global Railway couldn’t make it happen, and closed the YSD Ohio plant in Dec 2005.  Odd, because they seemed to have a monopoly on Plug Doors.  (Do they even have a competitor?) 
Greenbrier purchased the tooling a month later in Jan 2006 and moved it to their one of their fabrication plants (most likely in Oregon or Washington).  More importantly, Greenbrier also acquired the patents related to Plug Doors.   Recent Greenbrier reefers (such as the ones for CryoTrans, Lineage, and UP) have Plug Doors that are EXACTLY the same as the insulated version found on the Frostline Reefers (with the exception that the entire door is stitch welded, no rivets).  This also explains why their Plug Doors look like they came off of a YSD assembly line, but do not have “YSD” on them. 
Market Leverage
Greenbrier will offer Plug Doors and components to railroads, and even other railcar builders.  This is a smart move since it will help maintain market dominance.  (Otherwise, it opens the door for a competitor to fill a need with a similar Plug Door design.)  Railcar Departments are already familiar with YSD Plug Doors, and the transition in ownership is seamless.  This puts pressure on competing railcar builders to use those same Plug Doors in their designs.  Greenbrier will be able to more easily underbid those competitors, since they control Plug Door supply. 
It is very possible most railcars built with a Plug Door will be coming from a Greenbrier assembly line for quite a while.  ;-)

Edited 1 time(s). Last edit at 11/15/22 00:00 by tmotor.

Date: 11/15/22 12:56
Re: BNSF 72’ Frostline Reefer (Part 10) – Insulated Plug Door
Author: gandydancer4

Loved this entire series. You've done excellent research. 

Date: 11/15/22 23:05
Re: BNSF 72’ Frostline Reefer (Part 10) – Insulated Plug Door
Author: tmotor

Season's Greetings, gandydancer4 !

> Loved this entire series. You've done excellent research. 

Thank you for the kinds words of encouragement!  :-D

TrainOrders is one of the few places that I can share this journey, and have folks enjoy it as much as I do.  Though the Internet has lots of resources to help with research, sometimes the information needed requires "boots on the ground".  It gives me a reason to be trackside, to pursue documenting one of my favorite railcars.  Can't think of a better way to spend a day!

Take care and God bless!

Edited 2 time(s). Last edit at 11/15/22 23:06 by tmotor.

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