After Sales Service

¬ęBack Checking the Spider Bushing on the Sandvik Cones - CH420, CH430 & CH440

What is the spider bushing?

 

The Spider bushing is located at in the top shell and is responsible for supporting the top of the main shaft.

 

The figure below shows a section view of the crusher and an ISO section of the cone body. The support from the spider bushing and inner eccentric can be observed.

 

 

Figure 1 above taken from the CH430 maintenance manual

 

 

  1. Spider cap
  2. Spider bushing
  3. Head nut
  4. Mantle
  5. Concave ring
  6. Mainshaft with head centre
  7. Eccentric wearing plate
  8. Bottomshell bushing
  9. Eccentric
  10. Eccentric bushing
  11. Step bearing
  12. Hydroset piston
  13. Pinionshaft housing
  14. Pinionshaft
  15. Dust collar
  16. Locating bar
  17. Dust seal ring
  18. Bottomshell
  19. Topshell
  20. Filler ring

 

Why the spider bushing is important?

 

The Spider bushing has an hour glass figure and as such it has a very tight clearance.  Once the spider bushing no longer supports the main shaft, the bottom of the main shaft exerts a large amount of force on inner eccentric bushing.

 

Figure 3 below shows the logic behind the step bushing and the inner eccentric bushing. Imaging holding the bottom of the pencil securely and exerting a force as per the red arrows. This would cause large stress to be exerted at the bottom of the pencil.  This is the same logic that applies when the spider bushing is worn.

 

 

Figure 3 taken from Sandvik training files

 

What can happen when the spider bushing is not maintained?

 

  • Burnt inner and outer eccentric bushing
  • Sized main shaft
  • Damaged main shaft and shaft sleeve
  • Damaged step bearings 
  • Damaged locating bar

 

In other words, not maintaining this item will cause serious damage to internal mechanical components of your cone crusher.

 

How do you measure the spider bushing clearance and what should the clearance be?

 

 

  • Drop the main shaft to the bottom position
  • Stop the machine and implement a lockout procedure
  • Ensure the crushing chamber is clean and remove the spider cap
  • Use a clean bucket and collect the grease from the spider housing
  • Inspect the grease and replace if necessary
  • Mark the feeler gauge with the "L" length in table 1 below (use masking tape or a small O-ring)
  • Insert the feeler gauge until it reaches the "L" length on the top of the spider bush and check the clearance (start with a small feeler gauge and work upward).  Check clearance around the entire diameter
  • Inspect the spider bushing dust seal and replace if necessary
  • Inspect main shaft sleeve and spider bushing for abnormal wear
  • If clearance is correct then note it down in the log of the machine (best to keep a log for history on the machine)
  • If the clearance is incorrect (exceeds "S" value in table 1 below) replace the spider bushing and re-check the clearance.  If the clearance is still incorrect then the main shaft sleeve will need to be replaced
  • Inspect O-ring on spider cap and re-assemble
  • Check grease level in spider bushing and add if necessary

 

Figure 4 above show

s the correct grease level (dotted line) in the spider housing taken from Sandvik training files

 

 

"S" is the maximum clearance value between the spider bushing and main shaft sleeve at the fulcrum point.

 

"L" is the distance at which the "S" clearance must be measured to obtain the fulcrum point.

 

Table 1:   

CH420        S=1.6mm        L=75mm

CH430        S=1.9mm        L=103mm

CH440        S=2.1mm        L=165mm

 

 

Figure 5 above shows the "L" and "S" measurements taken from Sandvik training files

 

Figure 6 above shows the use of a feeler gauge to measure spider bushing clearance

 

How often should it be measured?

 

Every 250 hours and every liner change

 

Notes:

Always refer to the Sandvik cone manuals specific to your machine for detailed maintenance guidelines

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