Most of the pulleys in a conveyor system are in one of the following three forms: round, I-shaped or capped tubular. Any such pulley can be designed as timing slot with drive flange, convex channel and traditional timing tooth.
● Round: due to the low cost of round pulley, most system designs use round pulley. Generally, the size of round pulley is 150 mm in maximum outer diameter and 100 mm in maximum width.
● I-shape: With the increase of diameter and width, the problem of rotation inertia may require the belt pulley to have I-shape section. When the I-section is processed and put into the round pulley, the integrity of the pulley should be maintained, and the weight should be greatly reduced, so as to reduce the effect of rotation inertia. The weight of I-beam can be further reduced by machining holes on the web of I-beam.
● Cover tube shape: this kind of belt pulley adds end caps at both ends of the pipe, so that the pipe wall has enough thickness to ensure appropriate strength. Then, the capping assembly is processed to meet the strict specifications of roundness and concentricity. It's important to reduce weight without affecting strength.

Belt pulley material：
In order to meet the specific application requirements, various materials can be used to manufacture the pulley.
● Aluminum: aluminum which has been anodized by hard coating is a common material. This combination has the characteristics of firmness, light weight, wear resistance, low cost and high efficiency. However, extreme temperature may be a limiting factor, and exhaust in a vacuum environment may become a problem.
● Stainless steel: In corrosive operating environment, stainless steel is a good choice. Stainless steel also has excellent wear resistance and strength. There are many different alloys available, each with special advantages
● Nonmetallic materials: some plastics have excellent wear resistance and strength. In some applications and in a large number of applications, plastic pulleys are cheaper than metal pulleys.

Pulley type：
Although pulleys come in a variety of forms, materials, and design features, pulleys are usually used for one of two purposes: friction drive or timing.
● Friction drive: friction drive wheels usually have a flat surface without timing elements.
Drum pulleys are not usually recommended. To use drum pulleys, two geometry can be used: drum and trapezoid. The pressure of drum convex face metal belt is smaller, but it is difficult to process and cost higher. The trapezoidal convex surface has low cost, high efficiency and good performance, but it should be avoided to be used in the application of high belt tension load due to the pressure rise.
●  Synchronous: the synchronous belt has teeth or grooves, which are radially distributed around the outer diameter of the pulley body. The timing hole is fixed on the metal belt by the gear teeth; The cavity groove enables the driving lug to be fixed on the inner diameter of the metal belt. It is worth noting that even in such pulleys, the drive is done by the friction generated between the flat belt and the pulley surface. Teeth or grooves are only used for timing, not for power transmission.
The synchronizing elements (especially the synchronizing gear teeth) must be rigid. Hardness is essential to ensure that wear from continuous use of belts and pulleys is minimized.
In the design of two wheel timing system, the driving wheel should be timing, and the idle wheel (or driven wheel) should be friction driving wheel. If necessary, it should have a convex channel for the convex plate.

Pulley tolerance（Maximum diameter 355mm）

	Synchronous wheel	Synchronous wheel
Conveyor support diameter (outer diameter)	±0.025mm	±0.051mm
Front width	±0.127mm	±0.127mm
Borehole diameter	+0.025mm/-0.000mm	+0.050mm/-0.0000mm
Concentricity	0.025mm	0.025mm
Synchronization position	25 arcsec	Not applicable