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To Replace or Repair? That is the Question!

Thursday, October 1, 2009

I. Introduction
It could be a Tennant 800 Sweeper, perhaps a PowerBoss SW72, Nilfisk Advance 2052 that we are discussing in this episode, but it’s going to be an American Lincoln 7760. That is because all of these sweepers and sweeper/scrubbers have several common denominators:

  1. They all have a drive wheel motor.
  2. They all use hydraulics to propel these machines.
  3. They all have an IC Engine as the main power supply.
  4. Preventative maintenance, trouble shooting and the necessary corrections/fixes are similar in nature.

II. The Machine
American Lincoln manufactures the Model #7760. This machine is also known as Clarke-American and Alto. The 7760 are a large rider sweeper/scrubber weighing in at around 4,500 pounds (a little over 2 tons). If you have a large warehouse (let’s say around 400,000 to 500,00 square feet) this is the machine for you. With a full-blown sweeper/scrubber system, the operator can sweep or scrub. Of course, the operator can do both, sweep and scrub.

Manufactured beginning around 1996 through 2006. It is a proven machine with the next generation being the Model 7765.

III. Problems, Cause and possible Solutions
The rear drive wheel motor is leaking profusely. Since the motor is hydraulic, the fluid can not be tolerated on any floor surface for a long period of time. It has to be solved immediately. So the question comes down to: Do you repair the motor or outright replace it with a new one? Let’s look into the number of possibilities.

  1. Of course, one can just replace it with a new unit. The whole unit is not cheap. Roughly, the list is usually $1,000.00 to $1,500.00. This is typical among the different sweeper manufacturers. However, this is probably the quickest method of getting your machine back up and running.
  2. One can do #1 and then tear into the old motor, perhaps repairing it for a spare. If you are the owner of more than one machine, this is a great idea for many. This helps your budget long term.
  3. If you have some time between cleanings, resealing the motor is a great way to hold to your budget; as long as resealing does the fix. There is not a worse time than needing your scrubber and being down for an extended period of time.
  4. The Rebuild: I would highly advise that you know or have some experience with hydraulics and hydraulic motor before you tear into a wheel motor. But if you are determined this is what sequence I suggest.

A. Lay the motor on its end with the shaft facing up. Make sure you have drained the oil with all of the fluid before proceeding.

B. Loosen all the flange bolts in a clock-wise fashion; Starting at the 2 o’clock bolt. Remove all bolts.

C. Carefully remove the mounting flange. This should expose the main shaft and bearing.

D. Remove the main shaft and bearing

E. At this point most fixes can be made. You can purchase what I call the “shaft-end seal kit.” This kit includes all the seals, o’rings etc. to mend this front half of your motor. In most cases (maybe 75%) this repair kit is all you need. However, if you tear into this motor there are tale-tell signs that more is needed and a front-end kit just isn’t enough:

a. When there are gouges in the metal of the
main bearing housing.

b. If there are minute slivers of metal, a seal
kit is not the answer. So pay attention and be aware of these factors.

There are many steps one can take to prolong the life of your drive motor and as far as that goes your entire hydraulic system. There are several above all others and are essential.

They are:

  1. Every 8 hours check the level of your hydraulic fluid. Check the fluid itself for grit and dirt. It should always have a clean color.
  2. Every 50 hours check and inspect all hydraulic hoses for cuts. Also inspect motors, valves etc. for leaks.
  3. Every 250 hours replace your hydraulic filter element.
  4. Every 400 hours drain old hydraulic fluid. Clean the hydraulic reservoir. Clean or replace hydraulic intake strainer. Install new hydraulic fluid.

There is much more on the subject we could discuss, I simply have run-out of time. If you have any questions or comments you can e-mail me at

Thanks for reading.

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