Abstract: Provided herein is technology relating to polymerization and producing polymers and particularly, but not exclusively, to methods, systems, and compositions for producing articles using three-dimensional printing and for improving control of polymerization using a polymerization photoinhibitor having fast back reaction kinetics such as hexaarylbiimidazole compounds and bridged hexaarylbiimidazole compounds.

Abstract: A self-positioning cushioning device adapted to be mounted in the end of a rail car sill includes a hydraulic cylinder and yoke. A piston rod extends from the cylinder and is joined to one end of a yoke. The other end of the yoke is joined to a rail car coupler through a drawbar. A preloaded stack of elastomer pads is confined in a pocket in the yoke between a pair of stop plates which extend laterally of the yoke to engage stops during movement of the yoke, rod and piston in response to buff and draft impacts. The cylinder is filled with pressurized hydraulic fluid which maintains the piston in a central neutral position with the stop plate adjacent to coupler held against stops on the rail car sill. Buff impacts are cushioned first by the cylinder and at the end of the stroke by both the cylinder and the spring. Draft impacts are cushioned by both the cylinder and the spring.

Abstract: A rail car buffer includes a standard capsule body and a high pressure hydraulic buffer spring only in the body. The hydraulic spring has a high compression ratio and is charged with very high pressure gas and hydraulic oil.

Abstract: A hydraulic-pneumatic cushioning device including a pressure indicator mounted on the device or remote from the device and connected to the pressure chamber within the cushioning device. The indicator includes a recess and a small pin extending into the recess. The position of the pin relative to the recess provides a tactile indication of the condition of the cushioning device.

Abstract: A lading protection device in the form of a shock absorber for a railway car including a cylinder containing a piston and a body of hydraulic fluid normally captive between the front face of the piston and the closed end of the cylinder. A flow control valve assembly, centered in the piston, mounts an orifice bushing defining a constricted circular orifice. The assembly includes a valve stem slidable in the piston with a spring at its inner end for pressing the stem in a direction to seal the orifice. The piston has a fluid passage extending therethrough and an annular separator piston defines, with the main piston, a receiving space into which the fluid flows upon impact. The space in back of the separator piston is filled with a charge of gas under high pressure so that when the impact has been dissipated the gas pressure acting upon the separator piston restores the fluid to its normal position in readiness for a succeeding impact.

Abstract: A backstop assembly for use with a cushioning device in the sill of a railway car. The cushioning device has a body, or cylinder, slidable endwise in the sill and carrying a car coupler at its outer end. The cylinder has a piston centered on the sill axis and a piston rod projecting from its inner end terminating in an enlarged end collar of circular cross section which is received in a backstop. The backstop is of rectangular box shape secured in the sill and having an inner end wall, outer end wall, top wall and parallel side walls, the end walls being axially spaced to form a chamber for loose, axially captive accommodation of the collar. The outer end wall has an arch-shaped clearance opening for loose accommodation of the piston rod.

Abstract: This disclosure relates to a frame adapted to be attached to a hopper car, a door plate slidably mounted on the frame, and an automatically engageable lock mounted on the frame adjacent the door plate and operable to hold the door plate closed when engaged. The lock includes pivotably mounted parts including a latch. One of the parts, which may be the latch, has a seal hole therein, and this seal hole is aligned with another seal hole in the frame when the lock is engaged. The seal holes are spaced from an adjacent edge of the frame a distance which is related to the size of the seal band such that there is little slack in the seal when the parts are coupled together. Further, the parts are shaped to require a substantial turning movement of the latch before the lock is disengaged, and the latch is unable to turn this distance because of the small amount of slack in the seal. Consequently the lock is prevented from accidentally disengaging when the seal is in place.

Abstract: A fabricated backstop for an end-of car cushioning unit in a railway car. The backstop is composed of two plate members or pieces which are welded separately to the inside of a center sill. One backstop piece is a generally U-shaped vertical plate member which is welded about its entire outer circumference to the inside of the center sill and provides an over-solid stop. The second backstop piece is a horizontal plate member positioned in contact with the rear face of the vertical plate member and having a cutout portion to receive an end collar of an end-of-car cushioning device. The horizontal plate member is welded at its front face to the vertical plate member and at its outer sides to the center sill to provide a rear buff stop and a rear draft stop.

Abstract: An end-of-car railway car cushioning unit has a cylinder and a cylindrical piston mounted in the cylinder with the piston rod secured to the piston extending through an opening in the rear end of the cylinder with the piston forming a high pressure fluid chamber on the front face thereof and a low pressure fluid chamber on the rear face thereof. The piston has a plurality of openings therethrough and a metering valve is mounted in each of the openings to meter fluid flow between the low pressure chamber and the high pressure chamber. Each metering valve has a buff flow passage and a restricted draft flow passage. At least one selected metering valve has a cylindrical extension thereon projecting from the front face of the piston and adapted to engage an end wall of the high pressure chamber as the piston approaches the end of its buff stroke to block the flow of fluid from the high pressure chamber to the associated metering valve adjacent the end of the buff stroke.