Buying with confidence
 |
| James Karaus |
February 2, 2005—Regardless of its age, used crawler cranes require careful inspection in order to make a well-informed purchase. With only a little extra effort, buyers can gain valuable insight into a crane's condition.
Assemble the crane
First, make sure the crane is assembled. Although you can inspect the components better when disassembled you really want to know how it works as a complete unit. You can learn a lot about a crane's condition as you walk up to it. More than 10% corrosion and you could be heading for expensive repairs. There are testers available to gauge the depth of the metal but visually any deep pits in the metal are signs that more investigation is needed. Even if the metal has been sandblasted and repainted you can still see pits in the metal. This is especially important on the boom itself, as it can have significant safety implications in the event of a corrosion-related failure.
Sheet metal rust is less of a concern as it is relatively easy and cheap to replace • but look behind those panels as they can remain damp with little air circulation; creating a corrosive atmosphere for the components behind. Open as many panels as you have time to; even badly rusted cabs shouldn't put you off if the rest of the machine is okay.
Check the tracks
Look at the tracks • how high off the ground does the machine sit? Badly worn tracks will sag as the intermediate rollers, tumbler, and idlers support the machine. The bronze bushings wear out, causing sagging and although this is relatively common, you have to factor in the expense of replacement.
Ask for the boom to be fully lowered in order to get a good look at it and also the pendant lines, the parts that support the rope. Also, remember to check the condition of the rope.
Inspect bearings or rollers
Older lattice cranes don't have a main bearing, but rather roller pads, hook rollers, and house rollers. Look for excessive wear and pitting. Newer cranes have a main bearing. A way to check its condition is to lower the boom, pick up a load then measure the degree of lean of the superstructure. Then check how much the bearing has rocked when the weight is unloaded. This can be done with a dial indicator.
Newer cranes have hydraulics • therefore check for leaks, damaged hoses, and monitor hydraulic pressure. Older machines use torque converters and gear trains to transfer power. Perform a range of operations and gauge smoothness and speed of response, and listen for unhealthy noises.
It's always a good idea to get an experienced mechanic to check out crawler cranes. Crawler cranes are built to last and are good second-hand buys—as long as you do your homework.
