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Preventive Maintenance for Sweepers


Maintaining Older Auxiliary Engine Throttle Cables

Anthony Libhart by Anthony Libhart, Schwarze Industries' Chief Engineer

Although we have tried several models and manufacturers through the years, every winter we receive calls about throttle cables sticking and breaking. One of the reasons is that these cables are a high use item with lots of friction between the cable and its surrounding sheath. On the other hand, the brand we have been using for the last several years is quite a high quality item. It is used throughout several other industries, including on fire trucks, and has a very low failure rate.

It is engineered to stay easily operable in all kinds of weather, from the heat of Florida to the sub-zero tundra of Alaska. If you or your drivers have had trouble with longevity of your throttle cables there are, however, some steps that you can take -- and one which we have taken -- to address the problem. First, keep in mind that the weak link of most cables is where they connect to the knob: the more resistance on the cable, the sooner it will break. Pushing and pulling on your throttle cable when it is binding is a sure way to end up with a broken cable. If it is hard to operate, you need to troubleshoot the reason and fix or replace it.

Buyers Products Company manufactures the cable used in several sweeper lines. Dick Rutkoski of Buyers says that problems usually arise from the operator not fully understanding how the cables are designed to work. So, we put together the following 'primer' on use of their cables:

Diagram The operator's end consists of three separate knobs, a red one and two black ones of differing sizes. The larger of the black knobs is for dialing in the target rpm level. The smaller "locking collar" knob then should be used to keep it set. The red knob is only an emergency quick release designed to immediately idle the engine down.

Something which can easily cause cable failure and throttle mechanism damage is for an operator to set the rpm by depressing the red knob and then pulling the plunger out. It is very difficult to tell when the cable has reached full extension using this method, and as a result it is extremely easy to cause damage. The only way the rpmÕs should be set is by turning the large black knob to the rpm level needed, then locking it in place using the small locking collar knob. When the red knob is used only for its designed purpose, as an emergency quick release, incidence of cable damage will be greatly reduced.

The second major cause of failure occurs when an operator tries to adjust the large black rpm knob while the assembly is still locked into place by the lock down collar. The cable is designed not to move until either the red quick release is depressed or the locking collar is released. Trying to move it without releasing one or the other of these can easily cause damage to the cable and/or the throttle mechanism on the auxiliary engine. Throttle action will be seriously affected once the inner cable or the throttle mechanism is bent, so make certain that all your sweeper operators understand how the throttle cable does and does not work.


That's what you can do, and here's what we have done. Because sweepers are operated under dusty conditions, it is easier than in most applications for dirt to get in between the inside cable and its outer cover. To counteract this, the Schwarze factory has recently started adding a 'cap and wiper' which attaches at the lower end of the throttle cable. It is designed to keep moisture, dirt and other contaminants from getting in between the cable and the cable jacket. This also improves resistance to freezing and keeps the cable working smoothly under virtually any kind of operating conditions.

This article is reprinted from American Sweeper magazine, v1 n1 1992.

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