Long-stroke shock absorbers
A long-stroke shock absorber is a component of a rail freight wagon which, as a shock absorbing device, is responsible for protecting sensitive cargo from peak loads that can occur in shunting services.
Reasons to install a long-stroke shock absorber
The problem in normal shunting operations is that forces up to four times the weight (4 G) can occur in the longitudinal direction of the car when walking and pushing on the car , while only 1 G occurs in the train composition while driving. These 4 G can be too high for a sensitive load or can only be held with a very high level of security. (To illustrate: To secure a machine component weighing 10 tons, you need securing means for each longitudinal direction of the car, with which you can lift four times the mass - i.e. 40 tons). The solution of transport as a caution wagon with a ban on expiry and pushing off is expensive and usually extends the transport time. For this reason, a solution is being sought for regular transports in which these 4 G are kept away from the load and limited to 1 G, but the wagon can still be handled normally. In addition to the sliding loading, the installation of a shock absorbing device in the wagon is a possible solution to this problem.
Structure of the car
Put simply, the loading area of the wagon is decoupled from the undercarriage so that both can move towards each other in the longitudinal direction of the wagon. This movement is braked by a damping device - the actual long-stroke shock absorber. The impulse of the approaching wagon and the moment of inertia of the load are reduced by the long-stroke shock absorber to such an extent that only 1 G acts on the load. Because of the movement of the loading area against the substructure, there is additional free space in these wagons that must be kept free. This is marked accordingly in Europe with a warning mark; according to UIC, this area to be kept clear must be marked yellow with black diagonal stripes.
Labelling
Wagons that are equipped with a long-stroke shock absorber have the letter j according to the UIC type designation system for freight wagons .
Applications
The long-stroke shock absorber is usually only used in a few special vehicles. In terms of numbers, it is most widespread among container wagons, but even with these only a small proportion of the entire wagon fleet is equipped with it.