How should collars be installed?

If you can, use collars as you receive them. Wiping the bore and applying a thin coat of light oil to the shaft may be advisable. Do not degrease.

Allow yourself some testing time, especially if you plan to plate, lubricate, or rework.

Use unplated (black) wrenches, if at all possible.

Never use a pipe or extender on the handle of the wrench.

As a preliminary step to production applications, it is advisable to use a manual wrench to establish proper torquing parameters for that specific application. We do not recommend that you use a pneumatic wrench as this could lead to applying too much torque.

To achieve maximum holding power with clamping collars, tighten the collar until a slight resistance to rotation is felt. Wring to final position then tighten to final tension. This ensures maximum squareness, good seating, and maximum holding ability.

Observe lower torquing standards for stainless steel hardware. Recommended torques are listed on the technical section of the website and the technical page of our catalog.

When should a collar not be used?

Collars should not be used to limit impact loads where people or property could be endangered if the collar failed. In designing any mechanism that calls for a person to be near moving parts, extreme care should be taken to ensure that moving parts are constrained to do exactly what they are supposed to do. A collar is not always enough. If there are shock loads present, these should be taken into consideration. The clamp type collar is more sensitive to shock loads than the set screw style. Keep in mind, that a collar that resists several hundred or even thousands of pounds in a static test, can be shifted with a two-pound hammer. To absorb shock, the use of Belleville washers or a resilient buffer may be in order.

Can a collar be welded?

YES, we have seen some excellent examples of welded collars. Because our mild steel and stainless steel materials contain sulfur and other additives, the lowest possible current and adequate ventilation should be employed. Be sure to remove screws before welding. However, in no cases should collars with zinc plating be welded. The welding process on a zinc plated product will produce noxious fumes. Welding can be done safely on a black oxide finished product. Extreme caution is recommended when welding imported collars because of the inconsistency of the material and finishes.

What if the set screw is harder than the shaft?

The set screw need only be slightly harder than the shaft for to make a good impingement on the shaft and therefore deliver its full holding power. However, if the set screw is softer or only as hard as the shaft the holding power will be reduced.

One can easily test to see if the set screw is harder than the shaft. Simply tighten the set-screw onto the shaft and then remove and examine the rim around the cup point. If the set-screw is harder, the rim itself will retain its sharp profile. If the set screw is softer or only as hard as the shaft, the rim will be flattened indicating no impingement and, therefore, reduced holding power.

What determines how strongly a collar grips a shaft?

The primary purpose of a shaft collar is to resist an axial load. That is to hold itself in place despite pressure along the axis of a shaft. The axial holding power is primarily a function of screw size and applied torque. However, other factors such as presence of oil, temperature, the finish and hardness of the shaft can impact the holding power.

What is stick-slip?

Stick-slip is the false impression you get when a screw has been tightened to an appropriate stress level when it has not. Instead of the screw rotating uniformly as the torquing effort continues, there can be a point before final torque readings have been achieved where this uniform rotation converts to a stop and start pattern. The torsioning effort on the screw is being absorbed as excess friction between the threads or the underside of the head and the mating parts of the clamp body instead of contributing to stress in the joint element. If the stresses are low, that collar will not hold well. This stick-slip condition can be elusive. A silky-smooth operation of the clamping screw during torquing is your best assurance that stick-slip is not present.

Use of torque wrenches will not help overcome stick-slip because, in fact, the springiness of most torque wrenches invites this condition.

What are suitable applications for a collar?

A collar is primarily a positioning device, with specific applications that vary widely. It is important the end-user test a new application of a collar carefully before use. We recommend that the end user design their collars and applications. Climax engineers are available to offer suggestions and guidance but the ultimate responsibility for determining the suitability of a collar for a particular application rests with the end-user.

CAD drawings of all Climax products are available. Contact you local stocking distributor or make a request via the "contact us" section of this website.

What do rigid couplings do?

Rigid couplings serve as compact, economical components for the timing, joining or aligning of shafts at lower speeds and torque, particularly where zero backlash is desired. They are not intended for use as a critical part of a drive line or as a substitute for flexible or universal joints or other power transmission devices. As they are applicable for aligned shafts only, they are the most basic but often most cost-effective coupling option.

What are the different types of rigid couplings?

There are two basic styles of rigid couplings: the set screw type and the clamping type, which comes in both one-piece and two-piece styles. Most couplings are available in steel, stainless steel and some smaller sizes in aluminum. Almost all couplings (except smaller bores) are available with a keyway for increased ability to transfer torque.

Set-Screw Coupling

The rigid set-screw coupling (Climax premium "RC"-Series) like the set-screw collar is secured to the shaft by a set-screw that impinges upon the shaft.

Clamping Couplings

One-Piece clamping couplings have four tangential screws that when tightened grip the shaft without marring it. The two-piece clamping coupling has eight tangential screws (four on each side) and can be assembled without removing other components that may be on the shaft.

How should rigid couplings be installed?

The clamping screws are arranged in pairs. Climax recommends that Climax Premium Clamping Couplings be installed by tightening the paired screws alternately, in several steps so that the tension is distributed evenly. As each screw is tensioned, it tends to relax any tension developed by its companion screw. Hence, tightening one screw completely before tightening the other could lead to an unequal distribution of tension. When disassembly tension should be relieved in a similar manner.

Can rigid couplings be used on misaligned shafts?