Lovejoy Curtis CJ648 Single Universal Joint

Lovejoy Curtis CJ648 is a single-type block and pin universal joint with a static breaking torque of 5,500 in-lb (621 Nm), a 1.25 in outside diameter and a 3.75 in overall length. It accepts a bore up to 1.00 in (25 mm) with no keyway and uses the quick take-apart construction that Lovejoy lists for sizes CJ645 to CJ655.

A take-apart universal joint for angular drives

Curtis universal joints are part of the Lovejoy line following its acquisition of Curtis Universal Joints. The CJ single type is a block and pin design intended to transmit rotation between shafts that are not in line. Lovejoy lists these features for the series: a quick and easy take-apart design with no special tooling required, built-in lubrication passages, lubrication covers (boots) available, a stainless steel option, and operating angles of up to 35 degrees.

The CJ648 sits in the middle of the range, which runs from the CJ641 with 140 in-lb breaking torque to the CJ655 at 131,000 in-lb. It is meant for offset drives where the shafts meet at an angle that a flexible coupling cannot take. Applications outside the catalogue tables are referred by Lovejoy to its engineering team.

Technical specifications

CJ single type sizes CJ645 to CJ652

Selecting a CJ universal joint

Lovejoy states that the breaking torque is not a recommended operating torque. The permissible working torque is determined by the RPM and the operating angle, and the catalogue directs readers to its operating torque figure and engineering team for specific limits. Provide the shaft diameters, keyways or square and hex sections, speed, working angle, duty cycle and environment so that the correct size, material and boot can be confirmed.

When the angle exceeds what a single joint can accept, the CJ double type offers extra angularity and allows standard units to operate at angles up to 70 degrees. For applications where the individual shaft ends do not need a universal joint, review the flexible alternatives in the same catalogue family.

Lubrication and maintenance

The parts of a universal joint should always be well lubricated, because lubrication reduces wear and extends service life. Lovejoy recommends a free-flowing lubricant before use and every 40-50 operating hours thereafter, using an NLGI 2 extreme pressure grease. Lubrication covers (boots) are available for protection. Because the CJ645 to CJ655 sizes are take-apart designs, worn components can be inspected and serviced without special tooling.

Where it is used

Curtis joints suit drives where shafts are offset and rotation must pass through an angle. For the rigid and flexible coupling ranges in the same segment, see KTR ROTEX jaw coupling and Flender N-EUPEX pin coupling.

Using universal joints in Oman and the GCC

Block and pin universal joints are used in the region on machinery where shafts meet at an angle, such as valve operators, steering and linkage drives, packaging and food machines, and agricultural and handling equipment. They are not intended to replace flexible couplings on high-speed pump and motor drives. The operating angle, speed and torque together decide the life of the joint, so the angle should be kept as small as the design allows and the joint should be selected with a margin on torque.

Dust and sand are the main enemies of an exposed universal joint. A lubrication cover (boot) keeps grease in and dirt out, and the stainless steel option helps on coastal sites or wash-down areas where corrosion is likely. Lubricate through the built-in passages at the intervals in the Lovejoy instructions, and check the joint for play during routine maintenance.

Information to send with an enquiry

• Torque, speed and maximum operating angle
• Bore sizes, keyways and any pinning or set screw requirement
• Steel or stainless steel, and whether a boot is needed
• Quantity and any drawing of the drive
• Whether a double joint or a telescopic shaft is also needed

Related Lovejoy products: Lovejoy 1060 Grid Coupling, Horizontal Split Cover, Lovejoy SX 158-6 Disc Coupling, SX-6 Series, Lovejoy CJ 42/55 Curved Jaw Coupling, Urethane Spider, Lovejoy S-Flex Endurance 8S Elastomeric Coupling, Lovejoy SIER-BATH FHSA 3 High-Speed Gear Coupling and Lovejoy HercuFlex FX 4 Flanged Gear Coupling.

Documents and quotation

The Lovejoy Curtis universal joint catalogue is hosted on this page. See Couplings and Shaft Locking Devices. Seven Star LLC is an independent supplier in Muscat; send the shaft data, torque, speed and angle for a quotation.