Checking the Spider Bushing on the Sandvik Cones – CH420, CH430 & CH440

Checking the Spider Bushing on the Sandvik Cones – CH420, CH430 & CH440 What is the spider bushing? The spider bushing is located in the top shell of the cone crusher and supports the top of the main shaft. The diagram below shows a section view of the crusher and an ISO section of the cone body, highlighting the support provided by the spider bushing and inner eccentric. Figure 1 – CH430 maintenance manual Key components (Figure 1) Spider cap Spider bushing Head nut Mantle Concave ring Mainshaft with head centre Eccentric wearing plate Bottomshell bushing Eccentric Eccentric bushing Step bearing Hydroset piston Pinionshaft housing Pinionshaft Dust collar Locating bar Dust seal ring Bottomshell Topshell Filler ring Why the spider bushing is important The spider bushing has an hourglass shape and a very tight clearance. Once it no longer supports the main shaft properly, the bottom of the main shaft exerts a large amount of force on the inner eccentric bushing. The logic is similar to holding the bottom of a pencil and applying force at the top—the bottom experiences significant stress. Figure 2 – Step and inner eccentric bushing stress illustration Correct grease levels in the spider housing are critical for proper function. “S” = maximum clearance between the spider bushing and main shaft sleeve at the fulcrum point “L” = distance at which the “S” clearance must be measured Spider bushing clearance specifications: Crusher S (mm) L (mm) CH420 1.6 75 CH430 1.9 103 CH440 2.1 165 Figure 3 – “L” and “S” measurements Figure 4 – Measuring spider bushing clearance with a feeler gauge How often should it be measured? Every 250 operating hours At every liner change Notes: Always consult the Sandvik cone crusher manual specific to your model for detailed maintenance guidelines.