Gates Logo

Polyflex® JBTM is synonymous with high power density in small spaces. Developed by Gates and produced to patented manufacturing processes, these belts provide more load-carrying capacity at higher speeds to small multiple V-belt precision drives. This results in significant cost savings and improved design freedom. Polyflex® JBTM belts are recommended for use on bench type milling machines, lathe drives, woodworking and metalworking machine spindle drives, computer peripheral equipment, small blowers, etc. They are available in 3M-JB, 5M-JB, 7M-JB and 11M-JB sections.


  • JB = Joined Belt construction improves stability.
  • Ribs relieve bending stress on small pulleys and provide lateral rigidity.
  • The 60° angle provides more undercord support to the tensile section and distributes the load more evenly.
  • Small cross-section meets special application needs such as high shaft speeds, small drive package size and smooth running requirements.
  • High modulus polyurethane compound with a high friction coefficient.
  • The precise casting method eliminates overlaps and layers.
  • Excellent adhesion of tensile cords and polyurethane compound leads to high fatigue resistance and long belt life.
  • Extra toughness. The polyurethane compound resists fatigue, wear and ozone.


  • Long belt life on small pulleys and compact drives.
  • Greater shaft speeds, up to 30,000 rpm.
  • High performance and smooth running for precision applications.
  • Cost savings and design freedom.
  • Avoids vibrations when subjected to shock loads..
  • Available on demand in Matched sets. Contact Customer Service for details.
  • Available on demand in MTQ (MTQ=Machine Tool Quality) execution (Except on 3M-JB). Contact Customer Service for details.
  • Temperature range: -54°C up to +85°C.
Sections and nominal dimensions
Section Standard numbers of ribs Width
Length range
(effective length - mm)
2 3 4 5
3M-JB X X     3 2.28 3.35 175 – 750
5M-JB X X X X 5 3.30 5.30 280 – 1500
7M-JB X X X X 7 5.33 8.50 490 – 2293
11M-JB X X     11 7.06 13.20 692 - 2282
Ordering Code
5M - Section
280 - Effective length (mm)
3 - Number of ribs (joined belt)
NOTE: For correct design and tensioning of the belt please use Gates DesignFlexTM ProTM Drive design software, available on
Identification Durable white marking indicating the belt type and white marking indicating the belt dimensions.