Non-demountable to demountable sheave conversion

A non-demountable sheave or spider assembly is one where the sheave is an integrated component of the spider. These are often called solid cast spiders. As the name implies, there is no means by which you can remove the sheave without replacing the entire spider assembly.

On the contrary, a demountable sheave, is removable and mounted to the spider assembly which allows elevator contractors the flexibility to service or replace one component without the other. Modern elevator equipment has evolved to have this basic feature which saves labor and costly shut down time.

Over forty years ago, Titan Machine perfected the process of converting non-demountable solid cast spiders to demountable assemblies. We have amassed hundreds of patterns allowing us to stock castings to dimensionally suit nearly any OEM non-demountable design. Often times we can convert, or, “rerim” as it’s often called, your spider assembly in just a few days.

In this highlight video we showcase the basic steps in our process.
1. After cleaning the spider and visually inspecting the assembly we begin by machining off the existing rope grooves.
2. Because of the popularity of the spider being showcased and many other OEM designs, we batch produce these replacement sheave rims and stock them to minimize turnaround times.
3. Once the solid cast spider and new sheave rim are complete with a precise and standard interference fit, the process of mating the two parts begins.
4. The new sheave rim is positioned on top of the spider and heated evenly causing expansion. This allows the sheave to slip over the larger diameter of the now demountable spider assembly and seat itself against the spiders flange.
5. Once cooled, the sheave will contract onto the spider. Thereafter, the pair is drilled in unison and fastened mechanically with bolts.
6. Now that the sheave has been replaced, many of our customers will opt to have the main bearings replaced ensuring that, once reinstalled, the spider assembly will function better than new!

If you have any additional questions please call us at 718.361.7848
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Friday, August 22, 2014