Chapter 33 : Transmission of Power by Belts and Ropes 675
33.7.TYPES OF BELT DRIVES
The power, from one pulley to another, may be transmitted by any one of the following two
types of belt drives :
1.Open belt drive 2. Cross belt drive.33.8.OPEN BELT DRIVE
In an open belt drive, the two wheels move in the same direction as shown in Fig. 33·4.Fig. 33.4. Open belt drive.
The driver A pulls the belt from one side (RQ in this case) and delivers it to the other side (LM
in this case). Thus the tension in the lower side belt will be more than that in the upper side. The lower
side belt (because of more tension) is known as tight side; whereas the upper side belt (because of less
tension) is known as slack side.
33.9.CROSS BELT DRIVE
Fig. 33.5. Cross belt drive.
In a cross belt drive, the wheels move in the opposite directions as shown in Fig. 33·5.
The driver A pulls the belt from one side (RQ in this case) and delivers it to the other (LM in
this case). Thus the tension in the belt RQ will be more than that in the belt LM. The belt RQ (because
of more tension) is known as tight side; whereas the belt LM (because of less tension) is known as
slack side.