Category: Power Transmission Devices

Example 15.3: Two pulleys of diameters 500 and 200 mm are mounted on two parallel shafts 2 m apart. These shafts are connected by a cross belt. Find the angle of contact of belt and pulley. If larger pulley rotates at 250 rpm and maximum permissible tension in the belt is 1 kN, find the power…

Let   T1 is tension in tight side of the belt     T2 is tension in slack side of the belt     θ is angle of lap of belt over the pulley     μ is coefficient of friction between the belt and pulley Figure 15.5 Tensions in Belt Consider a short length of belt subtending an angle δθ at the centre of the pulley as shown…

Cross-belt drive is used to provide reverse direction of rotation to driven shaft as the direction of rotation of driving shaft. Similar to open-belt drive, let A and B be the pulley centres and CD and EF be the common tangents to the two pulleys as shown in Figure 15.4. Figure 15.4 Crossed-belt Drive In Figure 15.4, belt length, L = 2 (Arc GC + CD + Arc DH) Example 15.2: Two shafts drive are…

Open-belt drive is used to provide same direction of rotation to driven shaft as the direction of rotation of driving shaft. Let L is length of belt for open drive       r is radius of smaller pulley       R is radius of larger pulley       C is centre distance between pulleys       β is angle subtended by each common tangent on centre of pulley (CD)…

When belt passes from slack to tight side, a certain portion of belt extends and again contracts when belt passes through tight to slack side. Due to fluctuation in length of the belt, there is relative motion between belt and pulley surface. This relative motion is known as creep. Considering the creep, velocity ratio can…

Velocity ratio is the ratio of speed of the driven pulley to that of the driving pulley. Let   N1 is rotational speed of the driving pulley          N2 is rotational speed of the driven pulley          D1 is diameter of driving pulley          D2 is diameter of driven pulley          t is thickness of the belt i.e., D1N1 = D2D2, where t is very small in comparison to D, therefore it…

Figure 15.2 shows flat belt and V-belt. In the flat belt drive, rim of pulley is slightly crowned which helps to keep the belt running centrally on the pulley rim as shown in Figure 15.2(a). For the V-belt drive, grooves are made on rim of pulley for wedging action. The belt does not touch the bottom of the…

In belt drive, the velocity of two shafts can be varied by variation in diameter of pulley on which belt is mounted. But in chain or gear drive, the velocity of two shafts is varied by variation in the number of teeth on sprocket and gear, respectively. If an unstretched belt is mounted on the…

Power transmission is a process to transmit motion from one shaft to another by using some connection between them like belt, rope, chain, and gears. To connect the shafts, mainly two types of connectors are used, one is flexible and other is rigid. In flexible types of connection, there is relative velocity between shaft and…