Shafts are mainly classified into two categories: by structural form and by load-bearing capacity. According to structural form, shafts can be divided into straight shafts, crankshafts, and flexible shafts; according to load-bearing capacity, they can be divided into rotating shafts, drive shafts, and spindles.
Classification by structural form:
Straight shaft: The axis is a straight line. This is the most common type in machinery and can be further divided into smooth shafts and stepped shafts.
Crankshaft: The axis is curved or broken. It is commonly used in equipment such as internal combustion engines and can convert reciprocating motion into rotary motion.
Flexible shaft: Made of multiple layers of wound steel wire, it is flexible and can transmit rotary motion to space-constrained or bending locations, such as in medical equipment.
Classification by load-bearing capacity:
Rotating shaft: It bears both bending moment and torque during operation. This is the most common type of shaft in machinery, such as the shaft in a speed reducer.
Drive shaft: It mainly transmits torque and basically does not bear bending moment, such as the drive shaft of a car.
A spindle is a pivot that only bears bending moment and does not transmit torque. It is used to support rotating parts, such as the axle (rotating spindle) of a railway vehicle or the pulley axle (fixed spindle).
