How to Replace a Spring

In an effort to promote proper maintenance procedures, below is a step-by-step guide to safely replacing pigtail coil springs.

Should a spring that needs to be replaced be found during inspection or while the unit is in operation, it must be replaced immediately to avoid overstressing remaining coil springs as well as causing structural damage to the machine.

Safety First:

• Lockout: Lockout all related machines being worked on in accordance with your facilities Lockout-Tagout procedures.
• Machines must be at Zero Mechanical State. (this normally means that the eccentric on the shaft will be hanging down.)
• Review the Safety section on page 1 of all of General Kinematics Service Manuals.

Procedure for changing coil springs:

1.) Losen and remove the mounting fasteners for the coil spring.

2.) Remove the spring by using a hydraulic jack or a porta power to lift the trough up just enough to take the pressure off the spring and slide it out.

3.) Leave the jack in place as you will need the space you’ve created to install the replacement spring.

4.) Once the spring assembly is out, inspect the mounting surfaces, verify that the surfaces of both the spring and hardware mounting surface are flat.

Look for gouging, dishing, or mushrooming of the mounting surfaces.

If the area is gouged out or damaged, then it must be repaired or replaced to ensure a flat mounting surface.

To repair a small area, it should be built up with a 7018 welding rod and then ground flat.

5.) Thoroughly clean the mounting surfaces of any dirt, debris, rust, etc..

Verify that the correct spring, same color, and size, is being used to replace the original spring.

6.) Insert the replacement spring into position.      

You may need to lift the trough slightly higher to get the new spring into place.

Do not hit the spring with a steel hammer, this will damage the spring. Use a rubber mallet or block of wood if necessary.

7.) The rotation of the pigtail on the coiled spring should be opposite of the coiled spring adjacent to it. Unless specified otherwise in the GK drawings for your unit.

It is critical that the coils on the new spring should not contact the coils of any other spring that may be near it there should always be a gap between coils.

8.) Next, the hardware should be installed as appropriate to the spring being replaced the hardware arrangement can be found on the -09 or -10 modules of the service manual of the machine being worked on.

It is important that the hardware assembly is properly seated and centered in the eye of the coil spring.

Hardware installation

First place the hard washer on the bolt.

Then place the bolt through the bracket in the eye of the spring then place the spring washer onto the bolt with the lowered edge facing the spring then another hard washer, followed by the security lock nut.

The hardware can then be torqued to the torque as specified in the torque table in the GK service manual for your machine.

To torque you can use a:

Hand torque wrench

Pneumatic torque wrench

Hydraulic torque wrench

If access does not allow for this method, you can use the “Turn of the Nut Method” as explained in the service manual.

Once the spring is securely installed:

9.)  Start the unit.

10.) Check the stroke and verify that the operating strokes on the machine are correct.

In rare instances, more than one spring may need to be replaced at a time.

If you have to replace a rash of springs over a short time period it’s possible that the springs were overstressed because the unit was operated over or under stroked condition.

In this situation, it’s recommended that the entire spring system be replaced one at a time.

If you’re going to change out all or many pigtail springs at one time please contact us, as there are additional steps that will need to be taken to ensure your safety and the longevity of your equipment.