PowerGrip® GT® Belt Drives

Polyflex ® JB ® Belt Drives
Advantages of
Joined Construction
The actual size of a Polyflex JB belt is relatively
small when compared to a conventional V-belt.
Small belts, just by their nature, have a slightly
lower torsional and lateral rigidity. Subsequently,
there is a possibility of turning over (Fig. 17) when
subjected to a misalignment, power surge or
vibrations at or near its natural frequency. To prevent
such stability problems, the belt is constructed with
the overcord connected or “joined” together as
shown in Fig. 18. Joining the strands limits the
possibility of a belt turning over on properly
maintained drives when subjected to various types
of load fluctuations and vibrations. The ribbed
overcord of the belt also helps increase torsional
and lateral rigidity and increases belt flexibility.
Figure 17 — Turned Over Belt
Figure 18 – Polyflex JB
Polyflex JB belts are manufactured with either two
or three belt strands joined together. Any
combination of Polyflex JB belts can be used on a
single drive in matched sets. For example, if six
belts are needed to transmit a load, matched sets of
two joined belts with three strands in each belt
would work as well as matched sets of three belts
with two strands in each belt (see Fig. 19).
Figure 19
Matched Sets
When more than one Gates Polyflex JB Belt (more
than 3 strands, see Joined Construction) is required
on a drive, matched sets of belts must be used. A
matched set of Polyflex JB belts is factory measured
and tied together. The belts are measured and
grouped within various length ranges. On multiple
belt drives (more than 3 strands) this assures that
each belt shares its proportion of the load being
transmitted. Contact Gates Customer Service for
availability.
Standard Polyflex JB
Belt Lengths
Below in table 26 are the standard belt lengths, with
each belt length available in both two and three
strands.
Standard Sheave
Diameters
Gates specifies standard sheave diameters to help
design a Polyflex JB drive. Listed below in table 27
are the standard sheave diameters. Contact Gates
Customer Service for availability.
Table 26 — Standard Polyflex JB Belt Lengths
*Designation Effective Length
*Designation Effective Length
No. (mm) (in)
No. (mm) (in)
5M280 280 11.0
5M670 670 26.4
5M290 290 11.4
5M690 690 27.2
5M300 300 11.8
5M710 710 28.0
5M307 307 12.1
5M730 730 28.7
5M315 315 12.4
5M750 750 29.5
5M325 325 12.8
5M775 775 30.5
5M335 335 13.2
5M800 800 31.5
5M345 345 13.6
5M825 825 32.5
5M355 355 14.0
5M850 850 33.5
5M365 365 14.4
5M875 875 34.4
5M375 375 14.8
5M900 900 35.4
5M387 387 15.2
5M925 925 36.4
5M400 400 15.7
5M950 950 37.4
5M412 412 16.2
5M975 975 38.4
5M425 425 16.7
5M1000 1000 39.4
5M437 437 17.2
5M1030 1030 40.6
5M450 450 17.7
5M1060 1060 41.7
5M462 462 18.2
5M1090 1090 42.9
5M475 475 18.7
5M1120 1120 44.1
5M487 487 19.2
5M1150 1150 45.3
5M500 500 19.7
5M1180 1180 46.5
5M515 515 20.3
5M1220 1220 48.0
5M530 530 20.9
5M1250 1250 49.2
5M545 545 21.5
5M1280 1280 50.4
5M560 560 22.0
5M1320 1320 52.0
5M580 580 22.8
5M1360 1360 53.5
5M600 600 23.6
5M1400 1400 55.1
5M615 615 24.2
5M1450 1450 57.1
5M630 630 24.8
5M1500 1500 59.1
5M650 650 25.6
*Designation No. may not necessarily agree with actual Effective Length.
Table 27 – 5M Standard Sheave Outside Diameters
English
(in)
Metric
(mm)
English
(in)
Metric
(mm)
English
(in)
Metric
(mm)
English
(in)
Metric
(mm)
1.04 26
1.48 38
2.48 63
9.84 250
1.10 28
1.57 40
3.15 80
12.40 315
1.17 30
1.67 42
3.94 100
15.70 400
1.24 32
1.77 45
4.92 125
1.32 34
1.87 48
6.30 160
1.40 36
1.97 50
7.87 200
68 The World’s Most Trusted Name in Belts, Hose & Hydraulics.