Double Joints – Alloy Steel and Stainless Steel
- Solid hubs in 14 sizes. Joints 7/8″ and larger have Curtis’ TakeApart™ feature for easy and economical disassembly and reassembly, with no special tooling required
- Universal joint hub modifications are available, including bores, keyways, set screw holes, cross pin holes, squares, hexes and splines.
- Afford extra misalignment with operating angles of up to 70°

Resources
About the Take-Apart Joint
Single Joint Additional Resources
We stock alloy steel and stainless steel Curtis universal joints in 14 sizes. Universal Joints 7⁄8” and larger have Curtis’ Take-Apart feature which allows for specialized modifications with no special tooling required. This feature makes it easy for the end user to disassemble the joint, machine component parts and reassemble without damaging the hubs, pins or center block.
Curtis Universal Double Joints share the advantages and features of the Curtis single joints:
- Extra angularity allows standard units to operate at angles up to 70°
- Firm, positive lockup of the entire assembly thanks to Curtis’ exclusive Tell-Tale Lock Ring
- Built-in lubrication passages with Curtis’ exclusive internal lubrication system
- Lubrication covers (boots) available in all sizes to retain lubrication and keep out contaminants, extending the life of the joint. Curtis Joints do not require grooves on hubs to retain boots
- Less galling and seizing because Curtis uses dissimilar materials on all bearing surfaces
- Maximum wear and strength from Curtis’ induction hardened forks
- Easy machinability due to Curtis’ soft hubs
- Smooth operations and longer life assured by close and well-controlled tolerances between mating parts and Curtis’ built-in lubrication system
- Perfect concentricity with hubs ground on center and centering holes provided on solid hubs to aid in machining
- Universal joint hub modifications are available, including bores, keyways, set screw holes, cross pin holes, squares, hexes and splines
Alloy Steel Joints
Curtis Alloy Steel Joints feature 4140-grade steel for all forks. Forks of 7⁄8 inch diameter and larger have induction-hardened bearing areas for strength and durability. The body (hubs) of the joints remain in an annealed state, which affords free machinability. Center blocks and pins are machined from 8620 alloy steel and are carburized and case hardened to generate superior wear characteristics yet remain ductile, thereby enabling the joint to handle shock loads without experiencing premature failure. Universal joint hub modifications are available per customer specifications, which include but not limited to bores, keyways, set screw holes, cross pin holes, squares, hexes and splines.
- Alloy steel joints features:
- 4140-grade steel for all forks. Forks of 7⁄8 inch diameter and larger have induction-hardened bearing areas for strength and durability.
- Center blocks and pins are machined from 8620 alloy steel and are carburized and case hardened to generate superior wear characteristics
Stainless Steel Joints
Many applications require corrosion resistant universal joints to assure sanitation or to avoid premature oxidation or deterioration. Curtis’ 303 grade stainless steel u-joints are particularly important, for example, to industries that use food processing equipment, and for machinery that comes in contact with corrosive chemicals or is exposed to water for long periods. Furnace applications also benefit from stainless steel, which better withstands high temperatures and other environmental extremes. Curtis stocks 303 stainless in all 14 sizes from 3⁄8″ to 4″. Stainless steel grades 304, 316 and others available by special order.
- Stainless steel joints features:
- Corrosion-resistant to assure sanitation or to avoid premature oxidation or deterioration
- 18-8 Type 303 Stainless, non-magnetic steel
- Dimensionally the same as alloy steel joints, except for OD tolerance
For assistance in ordering your universal joints, please refer to Curtis’ how to order instructions or contact the Curtis sales department for more information.
Alloy and Stainless steel joints are dimensionally the same except for O.D. tolerance
- Alloy steel O.D. tolerance is +.000-.003″
- Stainless steel O.D. tolerance is +/- .020″
NOTE #1. Large bearing pin is provided with an oil passage. 1.00″ through 4.00″ diameter joints are also fitted with a ball spring oil fitting to retain lubricant.
NOTE #2. Curtis standard single universal joints will operate through angles of 70°. For applications requiring greater angles, special design can be employed, enabling the joint to operate at angles up to 90°.
Model | Outside Diameter | Total Length | Centerline to Centerline | Centerline to End | Bore Diameter | Set Screw Size | Keyway Size |
ALLOY PN/STAINLESS PN | A | C | E | F/2 | B | H | I |
CJ641DB1SS/SS641DB1SS CJ641DB/SS641DB CJ641D/SS641D | 0.375 | 2.437 | 0.688 | 0.344 --- --- | 0.188 0.188 --- | 2-56 NC --- --- | --- |
CJ642DB1SS/SS642DB1SS CJ642DB/SS642DB CJ642D/SS642D | 0.500 | 2.813 | 0.813 | 0.375 --- --- | 0.250 0.250 --- | 4-40 NC --- --- | --- |
CJ643DBKW1SS/SS643DBKW1SS CJ643DB/SS643DB CJ643D/SS643D | 0.625 | 3.250 | 1.000 | 0.406 --- --- | 0.313 0.313 --- | 10-32 NF --- --- | 0.094 X 0.047 --- --- |
CJ644DBKW1SS/SS644DBKW1SS CJ644DB/SS644DB CJ644D/SS644D | 0.750 | 3.813 | 1.125 | 0.484 --- --- | 0.375 0.375 --- | 10-32 NF --- --- | 0.094 X 0.047 --- --- |
CJ645DBKW1SS/SS645DBKW1SS CJ645DB/SS645DB CJ645D/SS645D | 0.875 | 4.375 | 1.375 | 0.516 --- --- | 0.438 0.438 --- | 10-32 NF --- --- | 0.094 X 0.047 --- --- |
CJ646DBKW1SS/SS646DBKW1SS CJ646DB/SS646DB CJ646D/SS646D | 1.000 | 4.875 | 1.500 | 0.594 --- --- | 0.500 0.500 --- | 1/4-20 NC --- --- | 0.125 X 0.063 --- --- |
CJ647DBKW1SS/SS647DBKW1SS CJ647DB/SS647DB CJ647D/SS647D | 1.125 | 5.125 | 1.625 | 0.609 --- --- | 0.563 0.563 --- | 1/4-20 NC --- --- | 0.125 X 0.063 --- --- |
CJ648DBKW1SS/SS648DBKW1SS CJ648DB/SS648DB CJ648D/SS648D | 1.250 | 5.625 | 1.875 | 0.625 --- --- | 0.625 0.625 --- | 5/16-18 NC --- --- | 0.188 X 0.094 --- --- |
CJ650DBKW1SS/SS650DBKW1SS CJ650DB/SS650DB CJ650D/SS650D | 1.500 | 6.563 | 2.313 | 0.672 --- --- | 0.750 0.750 --- | 5/16-18 NC --- --- | 0.188 X 0.094 --- --- |
CJ651DBKW1SS/SS651DBKW1SS CJ651DB/SS651DB CJ651D/SS651D | 1.750 | 7.750 | 2.750 | 0.781 --- --- | 0.875 0.875 --- | 5/16-18 NC --- --- | 0.188 X 0.094 --- --- |
CJ652DBKW1SS/SS652DBKW1SS CJ652DB/SS652DB CJ652D/SS652D | 2.000 | 8.625 | 3.188 | 0.813 --- --- | 1.000 1.000 --- | 3/8-16 NC --- --- | 0.250 X 0.125 --- --- |
CJ653DBKW1SS/SS653DBKW1SS CJ653DB/SS653DB CJ653D/SS653D | 2.500 | 11.063 | 4.063 | 1.047 --- --- | 1.250 1.250 --- | 3/8-16 NC --- --- | 0.250 X 0.125 --- --- |
CJ654DBKW1SS/SS654DBKW1SS CJ654DB/SS654DB CJ654D/SS654D | 3.000 | 13.813 | 4.813 | 1.422 --- --- | 1.500 1.500 --- | 1/2-13 NC --- --- | 0.375 X 0.188 --- --- |
CJ655DBKW1SS/SS655DBKW1SS CJ655DB/SS655DB CJ655D/SS655D | 4.000 | 17.000 | 6.375 | 1.563 --- --- | 2.000 2.000 --- | 1/2-13 NC --- --- | 0.500 X 0.250 --- --- |
Alloy Steel | 303 Stainless Steel | |
Joint Diameter | Max. Static Torque Inch Pounds | |
3/8″ | 140 | 100 |
1/2″ | 425 | 375 |
5/8″ | 900 | 610 |
3/4″ | 1610 | 1000 |
7/8″ | 1800 | 1350 |
1″ | 3050 | 1900 |
1-1/8″ | 3500 | 2200 |
1-1/4″ | 5500 | 3600 |
1-1/2″ | 9000 | 7200 |
1-3/4″ | 14000 | 10700 |
2″ | 22000 | 15500 |
2-1/2″ | 32000 | 21000 |
3″ | 55000 | 34000 |
4″ | 131000 | 81000 |