Figure 5.1. Friction Draft Gears.
within the housing of both there are coil springs and friction units made up of plates and wedges.
As the coil springs begin to compress, they meet the resistance of the friction unit. The more the springs
compress the harder they bear against the friction plates and thus the more the resistance to the compression
pressure. The resistance action permits cars to be started smoothly; when pressure is released, the friction unit
prevents the springs from recoiling too rapidly. A draft gear operates the same way when a car is suddenly
pushed rather than pulled.
5.4. RUBBER DRAFT GEAR
Designed to fit the standard draft gear pocket in the underframe, the rubber draft gear has been used on
locomotives and passenger cars for over 30 years. Its use on freight equipment is gradually becoming more
frequent. At present, rubber draft gear is found on the Army's diesel-electric locomotives, on cars in ambulance
trains, and on some troop and kitchen cars. The gear unit, as seen in figure 5.3, includes a series of rubber plates
that take care of shocks during coupling.
5.5. COUPLER
A coupler does three things: connects one car with another, holds the connection, and then disconnects the
two cars. Cars built in this country before 1933 were equipped with what was known as the
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