The structure of the transmission chain consists of an inner link and an outer link. It is composed of five small components: inner chain plate, outer chain plate, pin shaft, sleeve, and roller. The quality of the chain depends on the pin shaft and sleeve.

1. Internally connected transmission chain: The motion (rotation and linear movement) of the actuator it is connected to belongs to an independent linear motion according to motion analysis, so the relative motion relationship between the actuator components must be strictly required. A transmission chain with this type of transmission chain connection property is called an internal connection transmission chain. Therefore, transmission mechanisms with uncertain or instantaneous transmission ratio changes in the internal transmission chain, such as belt drive, chain drive, friction drive, etc. For example, when machining threads on a horizontal lathe, the thread transmission between the spindle and the tool holder is an internal transmission chain with strict requirements for transmission ratio, which can ensure and obtain the required thread pitch.

2. External transmission chain: It is the transmission chain that connects the motion source and the machine tool actuator. It enables the actuator to move at a predetermined speed and transmit a certain amount of power, but does not require a strict transmission ratio relationship between the motion source and the actuator. The change in the transmission ratio of the external transmission chain only affects productivity and surface roughness, and does not affect the formation of the surface shape of the workpiece.

The types and characteristics of transmission chains are as follows:

1. The standard transmission roller chain is a universal transmission roller chain based on JIS and ANSI specifications.

2. Plate chain is a suspension chain composed of a chain plate and a pin shaft.

3. Stainless steel chains are stainless steel chains that can be used in special environments such as pharmaceuticals, water, and high temperatures.

4. Anti rust chains are chains with nickel plated surfaces.

5. The standard accessory chain is a chain with additional accessories on the standard roller chain for transmission.

6. Hollow pin chain is a chain connected by hollow pin shafts, and accessories such as pins and crossbars can be freely attached or removed according to customer requirements.

7. Double pitch roller chain (Type A) is a chain with double pitch of standard roller chain based on JIS and ANSI specifications. It is a low-speed transmission chain with an average length and relatively light weight, suitable for devices with long distance between axles

8. Double pitch roller chain (Type C) is a chain with double pitch of standard roller chain based on JIS and ANSI specifications., Mainly used for low-speed transmission and handling, with standard diameter S-shaped rollers and large diameter R-shaped rollers

9. Double pitch accessory roller chain is a chain with accessories attached to the double pitch roller chain, which is mainly used for conveying.

10. ISO-B roller chain is a roller chain based on ISO606-B, which is widely used in products imported from Britain, France, Germany and other places.

According to the use of transmission chain, it can also be divided into: short pitch roller chain for transmission, double pitch roller chain for transmission, sleeve chain for transmission, bent plate roller chain for heavy load transmission, tooth chain for transmission, stepless speed change chain, long pitch conveyor chain, short pitch roller conveyor chain, double pitch roller conveyor chain, double speed conveyor chain, plate chain.