Conti Synchroflex AT3 GEN III 639

Conti Synchroflex AT3 GEN III 639 – endless timing belt for precise industrial drives

Conti Synchroflex AT3 GEN III 639 combines a precise AT3 GEN III tooth geometry with a molded polyurethane body and longitudinally stable steel cord tension elements. The product has 213 teeth and a pitch length of 639 mm, which corresponds to a tooth pitch of 3 mm. The belt is used in synchronous drives where uniform movement and reproducible position are more important than the elasticity normally associated with a conventional V-belt or flat belt. The GEN III version is the reinforced high-performance construction 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 usual standard version.

Fixed specifications

• Pitch length: 639 mm
• Number of teeth: 213
• Tooth profile: AT3 GEN III
• Tooth pitch: 3 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.

Profile, tooth pitch and engagement

The metric AT geometry has trapezoidal teeth with a larger tooth volume than the standard T profile. The purpose is to distribute the load advantageously in the tooth mesh and achieve higher tooth strength without making the drive unnecessarily large. The profile requires suitable AT timing belt pulleys with the same pitch; a visual similarity to other profiles is not evidence of compatibility.

Belt construction

The endless PU construction combines low dead weight with high longitudinal rigidity. The steel cord tension elements are cast into the belt and are not intended to be exposed, damaged or sharply broken during installation. The wear resistance of the polyurethane and the strong bond to the cord are central to the belt's lifespan. Correct handling is therefore just as important as the correct choice of profile and length.

The execution must be correctly identified

GEN III is the reinforced high-performance version of the Conti Synchroflex series. The construction uses red high-performance polyurethane, more densely packed steel cord tension elements and a two-filament construction with balanced S and Z cords. Continental states up to 25% higher power transmission than the corresponding AT or ATP standard series. GEN III can use the standard profile timing belt pulleys, but the belt still needs to be dimensioned for the specific drive.

Areas of application

Continental cites small power drives, handling equipment, compact positioning axes and light synchronous drives as examples for this profile family. The examples describe the general application area of ​​the profile, but are not an approval for any specific installation. The final belt width and pretension must be selected based on the transmitted torque, starting and shock loads, operating time, pulley sizes, speed and the number of teeth in simultaneous engagement. For safety-critical or heavily loaded drives, an actual calculation should be made.

Width selection and price calculation

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.

Selection of discs for the profile

The pulleys and belt should be considered as a single tooth engagement. Proper AT3 GEN III geometry ensures that the load is distributed across the tooth flanks rather than concentrated on tooth tips or edges. The drive ratio is selected by the number of teeth on the pulleys, while the belt's 213 teeth and 639 mm pitch length determine the required combination of pulleys and center distance. When changing the drive, the geometry should be calculated.

How to avoid unnecessary wear and tear

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.

Profile and length must match

The product's 213 teeth provide a convenient length check. Multiplying the number of teeth by 3 mm gives a pitch length of 639 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 the AT3 GEN III; the same pitch number alone is not always sufficient.

Wear patterns and troubleshooting

Troubleshooting should start with pu location of the damage. Edge wear is typically associated with grooveing and alignment, while tooth skipping can be associated with too low tension, load peaks or too few teeth in mesh. Ctiming bars on the back can be caused by too small rollers, back bending or environmental influences. Do not simply replace the belt without also finding the mechanical cause.

Temperature, media and service

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.

Technical questions about the product

Conti Synchroflex AT3 GEN III 639: are the standard widths the only possible widths?

The documented supplier widths for this size include 6, 8, 10, 12, 16, 20, 25, 32 and 50 mm. The product page may also show intermediate sizes as cut widths when they are within the allowed range. This does not change the tooth profile or length, but the price is calculated based on the base width.

Is the Conti Synchroflex AT3 GEN III 639 welded?

No. The Conti Synchroflex series is manufactured as cast, endless timing belts. The belt therefore does not have a welded joint around the circumference. The cast process provides a uniform tooth pitch around the entire belt and a strong bond between the polyurethane and the cast steel cord tension elements.

How many teeth does the Conti Synchroflex AT3 GEN III 639 have?

The belt has 213 teeth. The number of teeth is calculated by dividing the pitch length of 639 mm by the tooth pitch of 3 mm. The result is 213, and this number can be used as an additional check when identifying an existing belt. A different number of teeth means a different pitch length.

Conti Synchroflex AT3 GEN III 639: what temperature can the belt work at?

The GEN III series is rated for temperatures up to +100°C. When operating close to the limit, load, cooling and environment must be assessed separately.

Conti Synchroflex AT3 GEN III 639: what does the steel cord mean for the function of the belt?

The steel cord tension members absorb the longitudinal tensile load and provide high longitudinal stiffness. This helps maintain pitch and position during operation. The cord must not be kinked, exposed or damaged during installation, as local damage can weaken the belt.

Conti Synchroflex AT3 GEN III 639: why can a timing belt make noise?

Noise can be caused by incorrect pretension, skewed pulleys, poor tooth profile compatibility, excessive speed, resonance or worn tooth grooves. Lubrication is not the solution. First check alignment, tension, pulley condition and whether the belt runs without abnormal side contact.

Conti Synchroflex AT3 GEN III 639: 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.

The most important thing about this size

Conti Synchroflex AT3 GEN III 639 is the correct size when the drive requires AT3 GEN III, 639 mm pitch length and 213 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.