Timing belt CXA 1328 8M - CONTI® SYNCHROFORCE

Timing belt CXA 1328 8M - CONTI® SYNCHROFORCE

Timing belt CXA 1328 8M - CONTI® SYNCHROFORCE is an endless rubber timing belt for synchronous power transmission in industrial belt drives. The profile is HTD 8M CXA, the length is 1328 mm, and the belt has 166 teeth. The teeth work in mesh with the timing belt pulley and maintain a fixed movement between the shafts.

Product data

• Effective length: 1328 mm
• Number of teeth: 166
• Tooth profile: HTD 8M CXA
• Tooth pitch: 8 mm
• Profile type: HTD 8M in CXA version
• Tooth height: 3.4 mm
• Belt height: 5.6 mm
• Standard widths: 20 mm, 30 mm, 50 mm and 85 mm
• Length tolerance: ±0.40 mm
• Material: Chloroprene rubber
• Reinforcement: Aramid reinforcement
• Tooth surface: Prepared polyamide tissue on the tooth side
• Series: CONTI® SYNCHROFORCE CXA

Construction and materials

The CXA series is constructed with a chloroprene-based rubber backing, chloroprene teeth, aramid reinforcement and a prepared polyamide fabric on the tooth surface. The backing and teeth are made of chloroprene-based rubber, while the aramid reinforcements are located as the load-bearing reinforcement in the belt. This provides a belt that can absorb tensile forces and still maintain synchronous function, while the rubber part can bend around the timing belt pulleys during repeated rotations.

The polyamide fabric on the teeth is an important part of the belt's wear surface. It lies between the tooth rubber and the profile of the timing belt pulley and contributes to lower friction, smoother engagement and better protection of the tooth surface. In a CXA belt, the material layers are not separate functions, but parts of an overall construction where flexibility, tensile strength and tooth stability must work simultaneously.

Profile and tooth engagement

The CXA 8M uses a metric tooth pitch of 8 mm. The HTD tooth shape has a semi-circular profile, which provides a large and stable engagement surface between the belt and the timing belt pulley. This shape is known for its high safety against tooth skipping, because the tooth can engage deeply and smoothly into the profile of the timing belt pulley. For this belt, the 1328 mm effective length means that the belt has 166 teeth distributed around the endless belt.

The semi-circular tooth shape provides a large engagement surface in the timing belt pulley and is suitable for power transmission with good safety against tooth skipping. The profile is also part of the CXA series, where ContiTech has combined tooth shape, reinforcement and rubber compound for operation under demanding loads. The technical length tolerance for this length class is ±0.40 mm. The tolerance covers the manufacturer's effective length and pulleybase deviation.

Operating characteristics

CONTI® SYNCHROFORCE CXA is designed for high tensile loads and high starting torques and can be used at belt speeds of up to 20 m/s. The high load capacity is due, among other things, to the specially developed reinforcement and the strong material bond between rubber, reinforcement and tooth surface. This gives the belt high resistance to tooth deformation and good reserve for high starting torques.

The belt transmits motion synchronously, so that the driving and driven shafts maintain a fixed speed ratio. It works without lubrication and is designed for maintenance-free operation. The optimized profile matching between the timing belt and timing belt pulley, together with the polyamide fabric on the tooth side, contributes to quiet operation. In demanding operation, this is an important property, because both tooth engagement and load variation can affect the sound level and stability.

Resistance to operating environment

The CXA version is temperature resistant from -20 °C to +100 °C depending on the application. The belt is ozone resistant, suitable for tropical climates, conditionally/moderately oil resistant and electrically conductive according to ISO 9563. These properties make the belt suitable for industrial environments where temperature, air, oily influences and static electricity can affect operation.

The rubber-based construction also provides some damping in the drive. The timing belt can therefore be used in solutions where a quieter and lighter transmission is desired than chain or sprocket drives. The function of the belt still depends on the mechanical structure around it, but the CXA construction itself is made to maintain strength and flexibility under repeated loads.

Application

In a belt drive with high torque and lower speed, the belt can work as a positive-locking transmission between shafts, where the tooth engagement carries the movement without slip. Higher-power machines, shaft drives, production equipment, conveyor systems and other belt drives where load and speed work together. It can be used in industrial systems where synchronous operation, high efficiency and stable power transmission without lubrication are required. The CXA series is particularly relevant in torque-loaded drives, where tensile strength and tooth stability are more important than maximum belt speed.

The effective length of 1328 mm and the CXA 8M profile make this belt a specific dimension in the series. The belt fits into timing belt pulleys with a corresponding tooth pitch and tooth shape. When timing belt pulleys and belt have the same tooth profile, the load is distributed over the teeth that work in mesh and the movement is transmitted without the slip known from friction-based belt types.

Installation and ongoing operation

In a synchronous belt drive, belt tension, the condition of the timing belt pulleys and the parallelism of the shafts are important for the life of the belt. A CXA belt works best when the tooth surfaces can move cleanly in and out of the profile of the timing belt pulleys. Too low a tension can cause unstable tooth engagement, while unnecessarily high tension can increase the load on bearings, shafts and reinforcement. A correctly constructed transmission utilizes the strength of the belt without overloading its materials.

The belt is endless without joints. This provides a uniform structure all the way around and is an advantage in dynamic operation because the belt does not have a weaker joint pu . The same construction makes the belt suitable for repeated accelerations, uniform rotational speed and operation with continuous tooth engagement.

Question about the belt

What does an HTD tooth shape mean?

HTD stands for High Torque Drive. The semi-circular tooth shape provides good protection against tooth skipping and is suitable for power transmission with high torque.

What does tooth division mean?

The tooth pitch is the center-to-center distance between two adjacent teeth measured along the belt's pitch line. An 8M belt has a tooth pitch of 8 mm.

What does CXA mean on this timing belt?

CXA is ContiTech's high-tensile-load version. The series uses aramid reinforcement and chloroprene-based rubber for belt drives with high torque and demanding starting conditions.

What does the fiberglass reinforcement in the belt do?

The aramid reinforcements act as reinforcement and help the belt maintain its length under load. This is important in synchronous belt drives, where tooth position and the effective length of the belt have a direct impact on operation.

Why is polyamide tissue on teeth important?

The polyamide fabric protects the tooth surface, reduces friction in the engagement and contributes to smoother operation between the belt and the timing belt pulley. This is especially relevant at higher speeds and repetitive loads.

The effective length is the pitch length of the belt and the length value used to identify the timing belt. The number of teeth follows from the length and the pitch. For this belt, 1328 mm length and 8 mm pitch give 166 teeth. This relationship is important because the number of teeth determines how the belt fits in relation to the number of teeth on the timing belt pulleys and the center distance in the drive.

The rubber matrix of the belt provides cushioning and flexibility, while the aramid reinforcements absorb the tensile load. The timing fabric on the inside is the part of the belt that works directly against the timing belt pulley. In practice, these parts must work together: the rubber must be able to bend around the timing belt pulleys, the reinforcement must limit length change, and the tooth surface must resist wear from repeated engagement.

The dimensions of the profile affect how the belt bends and how the tooth carries the load in the timing belt pulley. For 8M, the tooth pitch is 8 mm, the tooth height is 3.4 mm, and the total belt height is 5.6 mm. These measurements describe the profile itself and are not the same as the belt width, which depends on the individual belt variant.

The standard widths for this profile are 20 mm, 30 mm, 50 mm and 85 mm. The different widths allow the same length and tooth pitch to be used in belt drives with different power loads. A wider belt can distribute the load over a larger tooth surface, while a narrower belt can be an advantage where space and rotating mass must be kept to a minimum.

The electrical conductivity level according to ISO 9563 is a relevant property in many industrial environments where static charging should be limited. Together with ozone resistance, tropical resistance and conditional oil resistance, this results in a belt that is more robust to ambient conditions than a simpler standard timing belt. The temperature range for the CXA version is -20 °C to +100 °C, depending on the application.