Schnabel related terms

Updated 8/11/01


Axle Loading

Total weight on each axle expressed in Pounds per Axle ( or Thousands of Pounds, or "Kips", K per Axle). When load is not longitudinally centered on car, the axles of the truck closest to longitudinal center of gravity of load will carrying a greater total load than the axles of the truck farthest from the center of gravity of the load and their loading is Maximum Axle Loading, and is of more significance in most cases than Average Axle Loading.

Clearance Diagram

A graphic depiction for visually comparing load configurations with fixed obstruction configurations, or with car or load configurations on an adjacent track. A clearance diagram is oriented in an upright plane perpendicular (radial in a curve) to the centerline of a specified track and faces a stated timetable direction and is drawn in a stated scale. The Top of Rail Line and the Track Centerline are the two fundamental axes of a Clearance Diagram. Any track curvature adjacent to an obstruction should be explicitly stated ( including direction, left or right ) so that the resulting offsets can be figured for both the inside and the outside of the curve, in order to obtain estimated clearances for a specified load configuration.

Cooper E Loading

A live loading concept originally designed by Theodore Cooper in 1894 for the design of railroad bridges. The " E " originally stood for steam engine, and designated the axle load on the drivers ( drive wheels ).

Effective Width

Range, left to right, of actual distance of lateral extremities of car or load from Track Centerline, taking into account the midordinate and endswing offsets resulting from a specified maximum track curvature, truck or bolster centers, and end overhang. The maximum midordinate offset or endswing offset, whichever is greater, is doubled and added to the measured width of the car or load to give the value of the Effective Width.

Equivalent Width

When a load is not transversely symmetrical about the centerline of a car, the greater of the two half widths is doubled to obtain the Equivalent Width.

Heavy Duty Car

Car having weight capacity in excess of 100 tons.

Idler Car

Generally a non-load carrying flat car or gondola car that is used in train consist for: (1) Providing space for load end overhang that extends beyond striker of load car. (2) Providing connection between two bolster cars carrying an extremely long load. (3) Providing separation between loaded cars or locomotive when a load is extremely heavy. (4) Providing additional braking capacity to supplement the braking capacity of a heavily loaded car.

Lateral Shift

In a schnabel car, the capability of horizontally offsetting load and supporting arms perpendicular to Track Centerline in order to clear fixed obstructions or equipment on an adjacent track.


In a schnabel car, the capability of vertically raising (perpendicular to Top of Rail Line in superelevated track) or lowering load and supporting arms in order to clear fixed obstructions or equipment on an adjacent track.

Light Weight (LT WT)

Weight of empty railroad car expressed in pounds. This figure is stenciled on the car. also referred to as Tare Weight.

Load Limit (LD LMT)

Absolute maximum allowable weight of load, including both net weight and dunnage, that a freight car is authorized to carry. This figure is stenciled on the car.

Pivot Pin

Cylindrical portion of bolster that rotates in base of bolster. Always perpendicular to deck of bolster car. Also applied to rotating pin of schnabel car arm.

Pivot Point

As seen in plan view, vertical axis about which bolster pins or schnabel arm pins rotate.

Reduced Pivot

In some models of schnabel cars the two pivot points are closer together than the two roller paths that distribute load weight from the arms to the centers of the main span bolsters. Designing a smaller distance between pivot points reduces the midordinate offset per degree of track curvature for a given length of load suspended between the arms.

Schnabel Car

A heavy duty, privately owned railroad freight car composed of two symmetrical halves that carry a load attached between the pivoting arms of each half of the car. The load and any accessories, such as suspension bars, become structurally a part of the entire car assemblage. In some cars, that portion including the load and arms can be hydraulically shifted horizontally or lifted vertically in order to clear fixed obstructions or equipment on an adjacent track.

Span Bolster

In a heavy duty car having more than two trucks, the structural connection between two adjacent trucks which links them into a single assemblage upon which one end of the car is supported.

Special Train

Train which is operated on an expedited schedule or under special service or transportation requirements specified by the consignor, consignee or the agent of either at a charge in addition to the applicable class or commodity rates or fares; or a train which is assembled in accordance with instructions given to a rail carrier by a consignor, consignee or agent of either. (Freight Tariff WTL 9100 Series, Item #130, Effective 01-29-86). An example of a Special Train could be a train used for movement of one or more cars carrying excess dimension or excess weight load(s) because speed restrictions and/or numerous stops would unnecessarily impede movement of a regular freight train and cause operating problems.



Background created from an image provided by Michael Dowd