HELI-CAL Flexured U-joints Provide Precise Operating Characteristics
A universal joint is a mechanical connection between rotating shafts
which are generally not in parallel, but intersecting. “U-joints”
transmit torque and motion.
U-joints are used in a variety of applications, wherever handling
significant angular misalignment is the main focus. Typical applications
include: articulating mechanisms, food processing equipment,
replacement for expensive gearboxes, and drives where motor position
must be moved angularly off centerline of the driven unit.
The oldest and most common type of u-joint is called the Cardan or Hooke
type joint. It consists of hub yokes, connected by a cross shaped
intermediate member. These popular u-joints are frequently used in
automotive applications. Because the design incorporates several
different piece parts, the moving parts of this type of u-joint usually
require lubrication; and as the joint wears, the amount of backlash or
free play within the joint itself grows. Even a lubricated Cardan
u-joint will require periodic maintenance, and may leak lubricant.
Performance wise, Cardan u-joints can transmit relatively high torque
with minimal radial loads. But, by design these u-joints have difficulty
compensating for parallel offset and axial misalignment. Cardan types
also introduce rotational inconsistencies into drive systems, a
phenomenon known as “non-constant velocity rotation.”
The “HELI-CAL Flexure” is an advanced and unique u-joint solution that
generally exceeds the capabilities of common u-joint designs. A Helical
u-joint is really a flexure capable of over 5° of angular misalignment.
It may accommodate up to 90° of angular misalignment in certain
circumstances. This type of u-joint will also compensate for axial and
parallel misalignment.
A frequent application of the Helical flexured u-joint is the direct
replacement for a 90° bevel gearbox. Gearboxes are expensive, and
usually need lubrication for their meshing gear surfaces and bearings.
Replacement with a maintenance free Helical flexured u-joint can save
money, both on initial purchase price and on maintenance costs. Flexured
u-joints can be beneficial most anywhere—for example, aerospace,
appliances, electronics, control mechanisms and drives, medical and
optical devices, sewing machines, instrumentation, and textile
machinery.
The performance capability of each HELI-CAL Flexure is determined by
characteristics such as:flexure outside diameter, inside diameter, coil
thickness, material, number of coils, and number of starts.
By altering these characteristics, torque capacity, angular and parallel
misalignment capabilities, torsional and lateral bending rates of
flexured u-joints can be made to suit specific specifications and/or
requirements.
By using a flexured u-joint, the customer benefits from:
» Choice of materials
» Infinite choice of end attachments
» Optimized misalignment and torque capacities
» A variety of torsional and lateral bending rates
» Ability to run in either manual or motor-driven applications
» Constant velocity
An added bonus: flexured u-joints do not have:
» Backlash
» Moving parts
» Maintenance and lubrication requirements
» Limited selection of capabilities and sizes
» Limited angular misalignment capability
Once the designer/customer provides Helical with the performance
requirements for his/her device, machine, or equipment, a specific
flexure design is developed that will meet or exceed application
requirements. An attachment may also be specified to securely interface
with adjacent components. The result is a HELI-CAL flexured u-joint that
works as an integral part of the customer’s application.
HELI-CAL flexured u-joints are tailor-made for customer applications,
using customers’ specific requirements as a starting point. The finished
product is a HELI-CAL flexured u-joint that “fits like a glove” in the
device, machine, or equipment.
Helical Products Company, with its unique HELI-CAL Flexure, covers most
u-joint requirements. Whether the application requires just a small
angle of slightly more than 5° or one calling for a 90° bend, Helical
has a “flexure” answer. This “answer” employs the infinitely variable
HELI-CAL Flexure, with its amazing range of variable characteristics. No
longer is it necessary to use a “one size fits all” approach to
u-joints.