Can someone explain the use of brake wheels here?

[Freight Train]

I just ran across this photo of a Frisco DD box that has two brake wheels at the sides of each door. The wheels look to be attached to tracks on each side of the door to open with some sort of gearing track. So what was this car used for??

http://www.rr-fallenflags.org/slsf/slsf7086akg.jpg

[Bob Bufkin]

Those wheels were use to open and close the doors.  Don't know what this car might have carried. 

[jagged ben]

Could they have been used to fix the doors in a certain open position? 

I read somewhere that SP often used to leave doors open on boxcars carrying lumber to allow it to dry out if it was wet.  Just speculating this could be a similar use, allowing the doors to be fixed partially open depending how much airflow was desired.

[nkalanaga]

Ben:  I've seen similar cars, and always assumed it was just to make opening the door easier.  But your idea makes more sense.  Opening a door by hand can't be too hard, given that most cars don't have any fancy gadgets to make it easier.

[Freight Train]

This would actually be a neat thing to model on a Atlas 50' DD box car with the roof walk removed 
Thanks for everyone with your input on this. Make more sense to set the doors with a geared track so they don't move.

[mu26aeh]

Exactrail modeled the door opener on this Southern 50' Waffle Box Car

https://www.exactrail.com/ps-50-waffle-box-car-sou-brown-w-door-opener

[davefoxx]

One use of the door opener wheel was to prevent shippers from opening and closing the doors with their fork lifts, which could cause significant damage to the cars.

DFF

[nkalanaga]

That also makes sense.  Some cars had forklift pockets on the doors, so they could be pushed without damage, but after watching the operators at my new job, I don't know how helpful they would be.  We had one guy put his forks through the side of the warehouse, and several have hit the ten inch H columns supporting the production floor roof. 

Interesting that the railroads had to pay extra for a device to make opening the doors less convenient just to save the doors...  Too bad they couldn't bill the customers using the forklifts for the damage.

[Missaberoad]

As a forklift operator it is sad to see the damage others cause... I've seen more people then I care to admit put their mast through the roof of a trailer or hit the threshold of a doorway 

Bulged up roofs are also very common on boxcars... caused by forklift damage...
http://www.railcarphotos.com/PhotoDetails.php?PhotoID=82586
http://www.railcarphotos.com/PhotoDetails.php?PhotoID=32437
http://www.railcarphotos.com/PhotoDetails.php?PhotoID=60906

[nkalanaga]

I've seen the bulged roofs in trains.  Our plant doesn't have rail service, so that's one thing our operators can't do.  I don't think we've damaged a trailer in the 2.5 years I've been there, but since I'm not in "Logistics", it may just have been kept quiet.  They damage the building in one way or another every few months, and a couple times a year manage to drop a skid of parts, making a big mess, a lot of noise, work for Quality sorting the results, and usually getting fired.  The company doesn't like to pay for experienced people, and they get what they pay for.

I stay in the "Clean Room", which isn't very, with the spiders and moths, and away from forklifts and material storage areas.  My little corner is air conditioned, rare for the plant, relatively quiet, and the supervisors hate to put on the clean room coats and hair nets.  As long as I meet production goals they leave me alone!  I also get paid as well as the forklift operators, with a lot less hassle.

[wm-webb]

40 years ago worked after school for an appliance/tv dealer. He would get a boxcar load of washers and dryers. We would back up to the car with a pickup to unload. Most doors would open by hand, some would open with a strap attached to a Chevrolet pickup, all would open for a loader on a John Deere 4020.