Conti Synchroflex AT5 GEN III 420

Conti Synchroflex AT5 GEN III 420 – durable PU timing belt with stable tooth pitch

This AT5 GEN III timing belt is specified with a pitch length of 420 mm and 84 teeth. The ratio between length and number of teeth is fixed: 420 mm divided by 5 mm gives exactly 84 teeth. The Conti Synchroflex AT5 GEN III 420 is supplied as a cast, endless PU belt, so that there is no weld joint in the finished ring. The design is developed for synchronous operation and precise machine movements. The GEN III version is the reinforced high-performance design with red high-performance polyurethane and a denser, two-filament steel cord. It should therefore be treated as a separate product series and not as the regular standard version.

The most important product data

• Pitch length: 420 mm
• Number of teeth: 84
• Tooth profile: AT5 GEN III
• Tooth pitch: 5 mm
• Material: cast polyurethane with steel cord
• Brand: Conti Synchroflex

The technical data below describes the part of the product that does not change when a different belt width is selected. Pitch length, tooth pitch and number of teeth remain identical for all width choices. However, the width affects the available belt cross-section width and the price calculated on the product page. Correct sizing must always take into account torque, speed, number of teeth in mesh, pulley diameters, service factor and any counter-bending.

How tooth geometry works

In a synchronous belt drive, the movement is transmitted through the tooth flanks. The geometry of the AT profile is therefore crucial for both load distribution, noise level and position accuracy. A correct AT pulley supports the teeth according to the profile to which they are cast. If the pulley's tooth shape or pitch deviates, the load can be concentrated at a few pu and cause abnormal wear, even though the belt can apparently be mounted.

Belt construction

With the cast manufacturing method, the finished belt becomes an exact copy of a precision-machined shape. This is a major reason for the uniform tooth pitch and reproducible length. The steel cord is integrated into the polyurethane and contributes to position and angular precision. The design is suitable for synchronous drives, where a conventional elastic friction belt does not provide the desired repeatability.

The specific product version

The red GEN III construction is not just a color variant. It is developed with higher cord density and a special steel cord construction that provides increased tensile strength, better grooveing and the ability to carry higher loads. The catalog also specifies a temperature range up to +100 °C. Standard and GEN III must therefore be created and selected as separate products, even when the length and profile are the same.

Typical applications and sizing

The profile series is used in practice for tasks such as machine tools, pu , textile machines and positioning and conveying systems. Common to these machines is the need for a fixed transmission ratio and controlled tooth engagement. A timing belt can transmit both force and position, but the capacity cannot be assessed based on length alone. Width, profile version, wrap angle and load cycle are among the data that must be included in the selection.

How the width variants work

The belt width is not written in the product name because the same pitch length is collected on one product page. The starting pu is 6 mm. Integer widths from 6 to 50 mm can be selected on this product page. The original supplier widths for this length are 6, 8, 10, 12, 16, 20, 25, 32 and 50 mm. Other intermediate sizes are offered as cut-to-size versions of the same type of timing belt sleeve when they are within the selection shown. The number of teeth, pitch length and profile do not change when the width is changed.

Gear ratio, enclosure and tooth contact

The number of teeth on the pulleys affects both the gear ratio, deflection and how many belt teeth carry the load. A small pulley may be necessary in a compact drive, but it should not be selected without considering the minimum profile requirements and any counter deflection. Use timing belt pulleys with 5 mm pitch and the correct AT5 GEN III tooth shape, and check that the flanges do not damage the belt edge.

Pre-tensioning and disc alignment

Proper installation begins with clean, undamaged pulleys with the correct profile. Teeth and grooves should be checked for deposits, bars and wear before the new belt is fitted. The pretension should be based on the drive's calculation and should not be selected based on a random hand feel. After the initial run-in, it is a good idea to check grooveing, noise, temperature and whether the belt runs centrally.

Before ordering a replacement

The product's 84 teeth provide a convenient length check. Multiplying the number of teeth by 5 mm gives a pitch length of 420 mm. If an existing belt has a different number of teeth, it is not the same size, even though it may look almost the same length. Also check that the teeth on the pulleys match AT5 GEN III; the same pitch number alone is not always sufficient.

Wear patterns and troubleshooting

Uniform light polishing of the tooth flanks may be normal, but localised spalling, ctiming baring or severe wear should be investigated. Wear on one edge often indicates misalignment or persistent flange contact. Damage to tooth tips may be due to incorrect profile, foreign bodies or inadequate engagement. If cord becomes visible or the belt has a sharp break, it should not continue in service without assessment.

Maintenance-free does not mean control-free

Continental specifies a temperature range of up to +100 °C for the GEN III series. When operating close to the temperature limits, the drive must still be dimensioned according to the specific load and environmental conditions. The cast PU belt is maintenance-friendly and does not require lubricant. Regular visual inspection is still relevant: look for ctiming bars, frayed edges, shiny tooth flanks, foreign body impressions and abnormal side contact. Sudden changes in noise or grooveing can be signs of misalignment, too low tension or worn pulleys.

Answers to typical questions

Conti Synchroflex AT5 GEN III 420: can an old V-belt be directly replaced by this timing belt?

No. A timing belt requires timing belt pulleys with the correct profile and pitch, while a V-belt works by friction in V-grooves. A conversion therefore requires new pulleys and a dimensioning of the entire transmission. The product is intended as a timing belt, not as a universal replacement.

Conti Synchroflex AT5 GEN III 420: why is 6 mm chosen as the basic width?

6 mm is the width of the supplier item whose SKU is used as the main product's stock reference. Other widths are handled as choices under the same product because they are cut from the same type of timing belt sleeve. The base width also determines the percentage-based pricing in the webshop.

Conti Synchroflex AT5 GEN III 420: can the belt be shortened or assembled to a different length?

No. This is a cast endless timing belt with a fixed pitch length. It can be cut to width within the available options, but the circumference and number of teeth cannot be changed. If the length needs to be changed, a different cast belt size is required.

Conti Synchroflex AT5 GEN III 420: what is the difference between tooth pitch and pitch length?

The tooth pitch is the distance from one tooth to the next and is 5 mm for this profile. The pitch length is the entire nominal circumference in the cord line and is 420 mm. When the pitch length is divided by the tooth pitch, the belt has 84 teeth.

Conti Synchroflex AT5 GEN III 420: does the number of teeth change when the belt width is changed?

No. All width choices on this product page have the same pitch length of 420 mm and the same number of teeth of 84. Only the width of the belt, and thus the price and possible load capacity, changes. The width must still match the pulleys and the technical dimensioning.

Conti Synchroflex AT5 GEN III 420: can the belt be turned upside down on the pulleys?

The standard version is single-sided with teeth on the inside and a smooth back. It must run with the teeth in the corresponding tooth grooves; the back is not an alternative tooth side.

Conti Synchroflex AT5 GEN III 420: how to check if the length is correct?

Count the teeth and check the pitch. 84 teeth times 5 mm gives 420 mm pitch length. Then compare the profile and design with the marking or the machine's spare parts list. A measurement around the outside of the belt alone is not accurate enough.

Summary

Conti Synchroflex AT5 GEN III 420 is the correct size when the drive requires AT5 GEN III, 420 mm pitch length and 84 teeth. The belt is cast endless in PU with steel cord and must be used with timing belt pulleys that match the profile. Choose the width according to the technical load and always check the design, alignment and pretension before commissioning.