Benefits of Polyurethane Timing Belts

Date: April 04, 2024

Plastic molded belts offer advantages over all-metal belts in several ways. In applications involving controls and instrumentation, plastic types of belts are especially well suited. Polyurethane is molded over a stainless steel cable which acts as the force transmitting spine of the belt. Many of these belts are also available with an aramid fiber (i.e. Kevlar) spine which allows for greater flexibility. Additional benefits include:

precision polyurethane belts and chains

No Backlash

With no moving joints, our continuously molded belts are naturally flexible and accurate. They reflect the high accuracy of the mold and repeat the accuracy at every cycle of the molding process.

No Lubrication

These belts do not rely on metal-to-metal contact to transmit system torque. No lubrication is required at any time, at any speed. This allows the use of plastic molded belts in critical environments where control of dirt and other contaminants is essential, such as medical industry applications.

Silent Operation

These belts function noise-free due to a lack of rubbing metal surfaces and the absence of metal-to-metal contact as the belt traverses the sprockets.

Rust Proof

Corrosion is never a consideration or concern thanks to the fabrication and materials of Berg PU timing belts.

Flame Resistant

Polyurethane has greater flame resistance than other types of plastics because burning causes it to carbonize, rather than melt.


Plastic molded over stainless steel or aramid fiber cable results in a lighter assembly than a comparable all-steel construction.

End Configurations

While many uses of molded plastic belts require an endless configuration, there are conditions where reciprocating motion conveys an important advantage. The readily available spine allows these belts to be hard-mounted to a base or carriage by means of an end device that can be screwed or clamped to a convenient surface. These are the most efficient ways to use the molded plastic belts, because the full tensile strength of the steel spine can be used. In the endless configuration, the lower tensile strength of the splice must be used.

Design Flexibility

The use of molded plastic belts gives designers greater freedom of axis placement. No need to check catalogs to make sure a particular center distance placement will be allowed by fixed belt size availability. The range of lengths for molded plastic belts is infinite. Given the center distances and pulley sizes, the required length of belt can easily be calculated. Our Flex-E-Belt series contain a single spine, which results in a great deal of transverse flexibility. This characteristic allows some very unique designs to become a reality. These belts can be used in assemblies where the axes of the sprockets are not parallel.

Flex-E-Belts polyurethane gear drive belts


Flex-E-Gear belts were designed to operate on standard spur gears modified to allow for a belt-supporting shoulder on either side of the teeth. Belt transmission loads are shared by two parallel spines. These are encased in the polyurethane and transfer the tensile forces to the sprocket shoulders. This series is unique in that it allows the use of belts as well as standard spur gears. With this feature we can build a hybrid drive system where belts and spur gears can share the same component. The sprockets can be machined to an AGMA class quality thereby making this an excellent choice for precision motion control.


Flex-E-Gear belts polyurethane drive chains

Transverse Flexibility

V-belts are heavy duty, power transmission components. The molded plastic Pow-R-Vee series can tolerate greater variations in the angle of the sheave groove. Greater transverse flexibility allows for increased misalignment of the driving and driven sheave pulleys. Molded plastic belts can be spliced to size right on the instrument or equipment. This is advantageous for all of the Berg molded plastic belt families, and it is extremely useful for the Pow-R-Vee series. Here we are usually dealing with heavy devices which would require extended periods of time for disassembly, belt installation and subsequent reassembly. Cut to size, the steel spine exposed, the belt can be spliced in place thereby greatly reducing machinery downtime.

Pow-R-Vee belts polyurethane V-belts

Smaller Assembly

Timing belts are widely utilized in the transmission of data and information. Berg Flex-E-Grip molded plastic timing belts offer several advantages. With a steel spine, molded plastic belts (the same size as rubber belts) have superior strength and stretch characteristics. The patented “no walk” belt track eliminates the need for pulley flanges. Polyurethane molded timing belts can therefore be used in a smaller package because the pulleys are not wider than the belts.

Flex-E-Grip polyurethane timing belts

Advantages of Partnering with WM Berg for PU Timing Belts

Our alternative solutions for industry standard timing belts, V-belts, gear drives and roller chains offer improved performance, lowered costs and reduced downtime.

Our patented timing belts and chains have been manufactured in large quantities for many years. Special requirements can be built in with several available molding materials as well as material and makeup of the load-carrying spine.

Berg customers enjoy:

  • Short turnaround time on belts & chains
  • Anti-static material options
  • 10 different color options
  • Belts & chains cut to custom length
  • Next-level precision

PU timing belts are ideal for high-precision and critical applications in a variety of industries, including aerospace, healthcare, motion control, manufacturing, packaging, telecommunications, robotic technology, consumer goods and more.

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