# Working principle of traction machine

Traction sheave elevator drive as shown in Figure 2-2. Installed in the engine room motors and gearboxes, brakes and other components of traction machine, is the traction drive power. Traction wire ropes connecting through a sheave side car, end of the counterweight. As well in the car and on their Rails run along the shaft without rubbing, placed a guide wheel on the machine the two apart. Car and gravity traction wire rope for heavy pressure generated in the sheave grooves of friction. In this way, motor rotation driving traction wheel, drive wire rope, drag car, and the relative motion. That car up to weight; on the rise, decline in car. So, car in the shaft runs back and forth along the rail in the upper and lower elevator performing vertical transport tasks.

Relative motion is that the car and the towline and friction between the sheave to achieve. This force is called the towing power or a driving force. Run the elevator loads and car location and direction changes. For the elevator in the various cases have adequate towing power, the national standard GB 7588-1995 the provisions of the elevator safety code for the construction and installation:

Traction conditions must be met: T1/T2xC1xC2 ≤ EF alpha

In the formula: T1/T2--carry 125% load compartment located on the lowest floor and car at the top station of the two cases, large sheave on both sides of the towline static force and smaller ratio of static tension.

C1--, acceleration, deceleration and lift coefficients relating to the special installation situations, commonly known as the dynamic coefficients

C2--sheave Groove sections change due to wear of the influence coefficient (semi-circular or cut slots: C2=1, v-grooves: C2=1. 2).

EF α, f for the towline in traction grooves in the equivalent friction coefficient Alpha for the traction rope angle at the trailing idler. EF α is called traction coefficient. It qualified ratio of T1/T2, EF greater alpha, it means that T1/T2 and T1-T2 allow the value, the greater the allowed values, also showed that larger elevator capacity. Therefore, a elevator traction coefficient represents the hauling capacity of the elevators.