JACKET
A thin outer shell over a tank used to contain insulating material.

JACKET FLASHINGS
See Flashing.

JACKET HEAD
The portion of the jacket that covers each end of an insulated tank car.

JACKET SPACER
On insulated cars, any one of the numerous steel, foam, or wood spacers that are mounted between the tank and the jacket thus defining a uniform space for the insulation.

JACKING PAD
Steel plates usually attached to the underside of the body bolsters, near the sides of car, designed to support the weight of the car on jacks.

JIC
Joint Inspection Certificate; when two parties have the right to inspect the damages of a car.

JOURNAL
The part of a railcar axle on which the wheel bearing are mounted.

JUMBO PRESSURE CAR
Generally refers to pressure cars in excess of 30,000 gallons capacity.

JUNCTION
A point at which two or more carriers interchange freight. Also, a point where two lines of a railroad meet, usually with provision for operating trains from one line to the other.