The use of Ring Springs for the Draft Gear

Like the coupler themselves the draft gear was developed at some evolutionary stages, mainly to increase the capacity and the maximal forces. But higher capacity led the increased weight too.

1. Wedge Shoe Draft Gear of the Russian Railway

The wedge shoe draft gear for the SA3 coupler SCH-2-T of the Russian Railway didn't fulfil the requirements of the European railways. This design resulted in an uncontrollable behaviour of the spring characteristic because of continuous change between static and sliding friction.

Capacity 2230 kpm Masse 260 kg (573 pounds)

2. Draft Gear with Ring Springs - 1965

The design of draft gears with ring spring columns started with maximal forces of 55 Mp, later with 70 Mp including the prestruck spring. The design was aimed to get a flat spring characteristic for traction forces to minimize longitudinal forces in the train.

The 70 Mp draft gear was attached at a flange of the underframe - this wasn't according the regulations later established by OSShD and UIC. Other disadvantages were the small energy absorption and the large outer dimension.

Max. Pressure Force 55 Mp Max. Traction Force 55 Mp Energy Absorption 2000 kpm Weight 140 kg

Max. Pressure Force 70 Mp Max. Traction Force 54 Mp Energy Absorption 3400 kpm Weight 350 kg

Max. Pressure Force 55 Mp Max. Traction Force 55 Mp Energy Absorption 2000 kpm Weight 140 kg

Max. Pressure Force 70 Mp Max. Traction Force 54 Mp Energy Absorption 3400 kpm Weight 350 kg

3. Ring Spring Draft Gear

Safety tests of derailment and calculations of longitudinal forces in the train resulted in new requirements for the draft gear. New designed spring ring geometry and other material came out in the patented Ring Spring Draft Gear - the basis for further developments

The new draft gear includes two spring columns. The inner column works for draft force and the outer column bears the pressure. The draft gear is now suitable for assembling from below and from vehicle end.

Max. Pressure Force 130 Mp Max. Traction Force 62 Mp Energy Absorption 6650 kpm Weight 400 kg

4. The standardized Draft Gear GRK 110
    Final design 1971

After standardization of requirement between OSShD and UIC the final design of the OSShD-draft gear GRK 110 was established in 1971. There were two types: The type 1.974 for 4-axle -vehicles (end pressure force 137 Mp, end traction force 91 Mp) and the type 1.975 for 2-axle-vehicles (end pressure force 92 Mp, end traction force 61,5 Mp). In 1973 - after many tests - the design was ready for mass production.