Conti Synchroflex T5 690

Conti Synchroflex T5 690 – dimensionally stable timing belt for positioning and power transmission

Conti Synchroflex T5 690 is an endless, cast polyurethane timing belt with 138 teeth, 5 mm tooth pitch and a pitch length of 690 mm. It is intended for synchronous power transmission, where the driving and driven shafts must follow a fixed tooth ratio without the slippage known from friction-based belt drives. The pitch length is the nominal length measurement in the cord line of the belt and is therefore the measurement that must be compared with the existing belt, the machine's spare parts data and the installed timing belt pulleys. This is the standard version in the specified profile. It must not be confused with a possible GEN III version or a double-sided DL belt with the same pitch length.

Fixed specifications

• Pitch length: 690 mm
• Number of teeth: 138
• Tooth profile: T5
• 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

As a classic metric profile, the T-series is used in many machines where reliable synchronous movement is important. The tooth shape is trapezoidal, and the number in the profile designation indicates the tooth pitch in millimeters. The correct washer must therefore both have the same pitch and be manufactured for the T-profile. The wrong profile can lead to poor engagement, noise and rapid wear.

Cast polyurethane and steel cord

The belt body consists of wear-resistant polyurethane, which encloses high-strength steel cord. The materials each have their own function: PU forms the teeth and protects the belt against mechanical wear, while the cord tensioning elements provide high longitudinal stiffness and limit post-elongation. Continental describes the design as maintenance-friendly and lubrication-free. This does not mean that the drive can be ignored; pulleys, alignment and pretension should still be checked.

The execution must be correctly identified

The product is the regular Conti Synchroflex standard version in the specified profile. Standard and GEN III may have the same pitch length and number of teeth, but they are different product series with different material construction and capacity data. The same applies to a DL belt, which has teeth on both sides. When reordering, the entire profile designation should therefore be checked, not just the length.

Typical applications and sizing

The application examples in the catalogue include office machines, household appliances, positioning drives and control drives. This shows that the profile can be used in both power transmission and motion control. However, the specific belt must only be finally selected when the machine's torque, speed, centre distance and pulley geometry are known. When simply replacing a spare part, the safest method is usually to copy the documented profile, length, design and width.

Gear ratio, enclosure and tooth contact

The pulleys and belt should be considered as a single tooth engagement. Correct T5 geometry ensures that the load is distributed over 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 138 teeth and 690 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

When installing, the cord pullers must be protected against kinks and local pressure damage. The belt must not be pinched with pliers or a screwdriver, and it should not be folded sharply. Check that the pulleys have the same pitch and profile as the belt and that they are not worn out. A stable drive is achieved through the right combination of alignment, wrapping and calculated pretension.

Choosing belt width

The basic price applies to 6 mm, and the other widths are calculated with the same percentage logic as the existing PU timing belts in the webshop. Integer widths from 6 to 50 mm can be selected on this product page. A width of twice the basic width therefore costs 100% more, while a width of one and a half times the basic width gives approximately 50% extra. This price rule is a webshop calculation; it does not replace a technical dimensioning of the belt's load-bearing capacity.

What does belt wear indicate?

A properly running timing belt should move smoothly without continuous contact against one flange. Regularly check the teeth for deformation, the back for ctiming bars and the edges for frayed areas. Abnormal noise or heat can be an early sign of incorrect tension or pulley failure. A systematic check of pulleys and belt is more effective than trying to hide symptoms with lubricant.

Temperature, media and service

The standard material is specified for ambient temperatures from -30 °C to +80 °C. Applications close to the limits, especially below -10 °C or above +50 °C, may require special sizing. The molded 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 may indicate misalignment, too low tension or worn pulleys.

Checking when replacing

It is not enough to compare the total circumference of a belt. The correct replacement must have the same pitch, tooth profile and number of teeth as the existing drive. The width must match the pulleys and the required capacity, and a DL or GEN III version must be identified separately. If in doubt, pictures of the marking, tooth profile and pulleys can be used as a supplement, but a documented spare part designation is best.

Frequently Asked Questions

Conti Synchroflex T5 690: when should the timing belt pulleys be replaced?

Pulleys should be evaluated if the tooth grooves are worn, sharp, crooked or damaged. A new belt on worn pulleys may have poor load distribution and short life. Also check flanges for bars and side contact and the grooves for foreign objects.

Conti Synchroflex T5 690: 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 T5 690: can a wider belt always transmit twice as much?

Not necessarily. A larger width provides a more active belt cross-section and can increase the permissible load, but the drive capacity also depends on the profile, number of teeth in mesh, pulley size, speed, load factor and preload. The width should be selected by an overall calculation.

Conti Synchroflex T5 690: 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 T5 690: can the belt be installed by pressing it over the flange of the pulley?

This should be avoided. The belt should be installed by adjusting the center distance or following the correct installation procedure for the machine. Forcing it over a flange can damage the cord pullers, teeth or belt edge. After installation, the pulleys must be parallel and the pretension must be correct.

Conti Synchroflex T5 690: what is the difference between T5 and a GEN III belt?

This product is the standard version. GEN III is a separate reinforced series with red high-performance PU and denser, two-filament steel cord. The same profile and length therefore do not mean that the products are identical.

Conti Synchroflex T5 690: is the polyurethane oil and chemical resistant?

The standard PU is described as resistant to simple oils, grease and petrol as well as certain acids and bases. This does not mean universal chemical resistance. In the case of continuous contact, high concentrations or cleaning agents, the specific liquid, temperature and exposure time should be assessed.

Conti Synchroflex T5 690: what temperature can the belt work at?

The standard version is specified for ambient temperatures from -30 °C to +80 °C. At temperatures below -10 °C or above +50 °C, adapted sizing may be required.

Conclusion

In summary, this is a Conti Synchroflex PU timing belt with a fixed geometry of 5 mm pitch, 138 teeth and 690 mm pitch length. The width is selected separately, but does not change the length or number of teeth. A safe replacement requires that the entire designation and the specific version match the machine documentation.