Specifying stochastic objects in a hierarchical graphics system

A brake rigging for a two-axle four-wheel railway car truck which embodies a brake cylinder disposed traversely between the side frames of the car truck and operatively connected to two parallel brake beams disposed on the respective opposite sides of a truck bolster through a linkage comprising a pair of spaced-apart bell-crank levers pivotally mounted on one of the brake beams, one arm of these bell-crank levers being pivotally connected respectively to the body of the brake cylinder and the exterior end of the piston rod of the brake cylinder piston, and the other arm of these levers being pivotally connected respectively to one end of one of a pair of rods, the other end of each of which is pivotally connected to the other brake beam. The traversely disposed brake cylinder, together with the pair of spaced-apart bell-crank levers, insure that the pair of rods connecting these levers to the other brake beam are so spaced apart one from the other as to be sufficiently disposed beneath the truck bolster adjacent the outer ends thereof as to enable adequate vertical movement of the bolster, as the result of truck spring deflection due to load on the car, without movement of the bolster into contact with these rods which would inhibit or prevent free movement thereof. Therefore, while the car is either empty or fully loaded, whenever fluid under pressure is supplied to the brake cylinder, the two brake beams are moved in opposite directions without hindrance by the bolster to cause the application of brake shoes carried by the brake beams to the tread surface of each wheel of the car truck with the same brake-applying force.