S-Flex Endurance® Couplings
- Easy to Install
- Maintenance Free
- No Lubrication
- Dampens Vibration and Controls Shock
- Torsionally Soft
- Double Engagement

Resources
The simple design of the S–Flex Endurance coupling ensures ease of assembly and reliable performance. No special tools are needed for installation or removal. The S–Flex Endurance couplings can be used in a wide variety of applications.
The S–Flex Endurance coupling design is comprised of three parts. Two flanges with internal teeth engage an elastomeric flexible sleeve with external teeth. Each flange is attached to the respective shaft of the driver and driven and torque is transmitted across the flanges through the sleeve. Misalignment and torsional shock loads are absorbed by shear deflection in the sleeve. The shear characteristic of the S–Flex Endurance coupling is very well suited to absorb impact loads.
The S–Flex Endurance coupling from Lovejoy offers combinations of flanges and sleeves which can be assembled to suit your specific application. Thirteen sizes are available with torque capabilities that range from 60 in-lbs (6.78 Nm) to 72,480 in-lbs (8189 Nm). The S–Flex flanges are offered in five models which are made from zinc die cast or cast iron. Sleeves are available in EPDM rubber, Neoprene, or Hytrel® to address a wide variety of application requirements.
S-Flex Endurance Coupling Product Selection
A standard S-Flex Endurance coupling is comprised of 3 parts:
- 2 flanges (J or S Type)
- 1 elastomeric sleeve (single piece or split types are available in EPDM, Neoprene, or Hytrel®)
Bushing & spacer S-Flex Endurance coupling configurations are also available.
PARALLEL: The S–Flex Endurance coupling accepts up to .062 inches of parallel misalignment without wear. The flexible coupling sleeve minimizes the radial loads imposed on equipment bearings, a problem commonly associated with parallel misalignment.
AXIAL: The S–Flex Endurance couplings can be used in applications which require a limited amount of shaft end-float without transferring thrust loads to equipment bearings. Axial movement of approximately 1/8 inch accepted.
ANGULAR: The flexing action of the elastomeric sleeve and the locking feature of the mating teeth allows the S–Flex Endurance coupling to effectively handle angular misalignment up to 1°.
TORSIONAL: S-Flex Endurance couplings effectively dampen torsional shock and vibration to protect connected equipment. The EPDM and Neoprene sleeves have torsional wind-up flexibility of 15° at their rated torque. Hytrel provides 7° wind-up.
J Type – Zinc Die Cast and Cast Iron (Bore Range: .375” to 1.437”)
S Type – Cast Iron (Bore Range: .5” to 5.5”)
B Type – Cast Iron with bushing bore*
SC Type – Cast Iron Spacer
T Type – Cast Iron with Taper-lock bushing
*Lovejoy does not provide bushings
ID1-ID2 |
EPDM |
Neoprene |
Hytrel® |
||||||||
|
Min Bore |
Max Bore |
Torque |
Max |
Torque |
Max |
Torque |
Max |
|||
Size |
(in) |
(in) |
(in-lbs) |
(Nm) |
RPM |
(in-lbs) |
(Nm) |
RPM |
(in-lbs) |
(Nm) |
RPM |
3 |
0.38 |
0.88 |
78 |
8.81 |
9,200 |
60 |
6.78 |
9,200 |
N/A |
N/A |
N/A |
4 |
0.50 |
1.00 |
156 |
17.63 |
7,600 |
120 |
13.56 |
7,600 |
N/A |
N/A |
N/A |
5 |
0.50 |
1.19 |
312 |
35.26 |
7,600 |
240 |
27.12 |
7,600 |
N/A |
N/A |
N/A |
6 |
0.63 |
1.44 |
585 |
66.09 |
6,000 |
450 |
50.84 |
6,000 |
1,800 |
203.37 |
6,000 |
7 |
0.63 |
1.63 |
940 |
106.20 |
5,250 |
725 |
81.91 |
5,250 |
2,875 |
324.83 |
5,250 |
8 |
0.75 |
1.94 |
1,475 |
166.66 |
4,500 |
1,135 |
128.24 |
4,500 |
4,530 |
511.82 |
4,500 |
9 |
0.88 |
2.38 |
2,340 |
264.38 |
3,750 |
1,800 |
203.37 |
3,750 |
7,200 |
813.49 |
3,750 |
10 |
1.13 |
2.75 |
3,735 |
422.00 |
3,600 |
2,875 |
324.83 |
3,600 |
11,350 |
1282,38 |
3,600 |
11 |
1.25 |
3.38 |
5,889 |
665.37 |
3,600 |
4,530 |
511.82 |
3,600 |
18,000 |
2033.73 |
3,600 |
12 |
1.50 |
3.88 |
9,360 |
1 057.54 |
2,800 |
7,200 |
813.49 |
2,800 |
31,500 |
3559.03 |
2,800 |
13 |
2.00 |
4.50 |
11,350 |
1 282.38 |
2,400 |
11,350 |
1282.38 |
2,400 |
47,268 |
5340.57 |
2,400 |
14 |
2.00 |
5.00 |
18,000 |
2 033.73 |
2,200 |
18,000 |
2033.73 |
2,200 |
72,480 |
8189.15 |
2,200 |
16 |
2.00 |
5.50 |
47,250 |
5 338.54 |
1,500 |
N/A |
N/A |
S-Flex Endurance sleeves are available in 3 configurations, and in 3 materials:
Solid Single Piece Sleeve (standard design)
-
JE – made of EPDM
-
JN – made of Neoprene
-
H – made of Hytrel®
Split Single Piece Sleeve (for easier installation)
-
JES – made of EPDM
-
JNS – made of Neoprene
Two Piece Sleeve w/ Retaining Ring (for applications with difficult shaft separation)
-
E – made of EPDM
-
N – made of Neoprene
-
HS – made of Hytrel®
Characteristics |
Temperature |
Misalignment |
Torsional |
|||
|
°F |
°C |
Angular |
Parallel |
Axial |
inches |
EPDM – Unless otherwise |
-30°F to 375°F |
-34°C to 135°C |
1° |
up to 0.062 |
0.125 |
up to 15° |
NEOPRENE – Neoprene |
0°F to 200°F |
-18°C to 93°C |
1° |
up to 0.062 |
0.125 |
up to 15° |
HYTREL® – Hytrel is a |
-65°F to 250°F |
-54°C to 121°C |
0.25° |
up to 0.035 |
0.125 |
up to 7° |
Please Note: CAD Files are located in the digital catalog.
For additional documentation (in PDF form), please download the S-Flex Endurance Coupling catalog (pdf) or contact Lovejoy customer service.