Cooling surface area A of the worm gear speed reducer

In our case: ;

Assume that K_t = 17; thearea of cooling surface A = 0.8 m²(table 6.12)

Thus .

Condition is satisfied.

7. ANALYSIS OF THE FLAT BELT DRIVE

Let us carry out the analysis of the flat belt drive if input power P₁ =6.6 kW; torque at the driving pulley T ₁=42 N∙m; velocity ratio of the belt drive u_bd =2.15; rotational speed of the driving pulley n ₁=1555 rpm.

7.1. Determine the diameter of the smaller(driving) pulley

d ₁» ,

where T ₁ is in N×mm.

Round off the diameter to the nearest standard value according to the following series: 63, 71, 80 90, 100, 112, 125, 140, 160, 180, 200, 224, 250, 280, 315, 355, 400, 450, 500, 560, 630, 710, 800, 900, 1000, 1120.

Assume d ₁=224 mm.

7.2. Determine the diameter of the larger pulley taking into account a relative speed loss ε = 0.01%

d ₂ = d ₁× u_bd ∙(1-ε)=224∙2.15∙(1-0.0001)=481.55mm.

and round off obtained magnitude according to the series of standard values.

Assume d ₂=500 mm.

7.3. Specify the velocity ratio of the belt drive

.

Error should be ε £ 4 %.

ε = < 4 %.

7.4. Determine the center distance

a = 2×(d ₁ + d ₂)= 2×(224 + 500)=1448mm.

7.5. Compute the contact angle

.

7.6. Determine the belt length

.

7.7. Determine the belt speed

.

7.8. Determine the turning (tangential) force

.

7.9. Choose the rubberized fabric belt according to table 7.1.

In our case we take the rubberized fabric belt Б 800 with the number of plies z = 3, d₀ = 1.5 mm thick each (including the rubber interlayers); the maximum allowable load to the ply p ₀ = 3 N/mm of width.

Table 7.1