More on Ratings

Aug 30th, 2013 | By | Category: Jack Schrock's Blog

Wreckers come in various sizes and configurations with each targeted to a particular application, which makes it easy for the large operator to make equipment selections. However, the smaller tower is often forced to a single model that will work for the majority of its needs. This can be tricky because in the interest of saving money, too many choose too small which can overwork a wrecker for those larger jobs.

A small wrecker doing a big job can be unsafe at best because an overworked wrecker is also an over-stressed wrecker. To briefly revisit wrecker design, the weakest link tells the ratings story. If the boom fails at 25,000 lbs. and the mounting system at 100,000 lbs., guess what? The wrecker fails at 25,000 lbs. or 12 ½ tons, regardless of just how robust other components might be. Herein is much of the problem with most shop-fabricated wreckers because too many are judged by appearance more than the slide rule and strain gauges. If it looks “stout” it must be, which is not always true because it is possible to have a very powerful (and heavy) wrecker seriously compromised by a single component that is too light for the job.

Having said that, let me say that every wrecker has a “range of operating efficiency” which means every piece part is designed to operate well below its point of failure so long as the overall “range of operating efficiency” (or ROE) is not exceeded. So, if you stay within this ROE, your wrecker should last a lifetime with just ordinary preventative maintenance. But, if you venture beyond the ROE just a single time, critical components can be overstressed to the point of eminent failure, which may or may not immediately occur. Remember the guy who said, ”I was only towing a Volkswagen when the boom bent.” The VW was not at fault, it was a previous event that caused the boom to bend.

If none of this makes sense, let me clarify it this way: If you want to handle both cars and trucks you need to confine your search to a quality 25- to 30-ton hydraulic wrecker with an underlift. But stay away from the buried excavator or loaded cement mixer because the first time you fight that beast you’ve overstressed your wrecker to the point that it can (and probably will) fail at most any inconvenient time. To handle those loads, confine your search to equipment that is accordingly designed and rated.