Steering Your Way ClearTuesday, June 1, 2010
If one were to drive an automobile, make a right turn and/or a left turn, the turning radius should be the same with no difference. Another words, it takes the same amount of space to turn in either direction.
However, a sweeper such as the Tennant Model 800 performing similar turns as the automobile is different. Do you know what you would find? You would discover that the left turn has a much sharper turning radius than if you were making a right turn. That’s correct, make a left turn the radius measures 135 inches where as the right turn radius exceeds 180 inches.
As there is a good reason for this I have had to explain to operators this fact throughout my years, and again, recently. So I thought that I might as well write an article about this.
For one thing, this vehicle is a three-wheel vehicle, not four. The one steer tire is in the back. This also operates as the drive or traction wheel. The other two are in front which also controls the braking of the vehicle.
To explain in simple terms, one could look at a child’s tricycle. The one steer tire is in front with the two in back. Now picture this tricycle in reverse with the two in front and the one in back.
Next, the question that usually follows is why does it turn in a small radius to the left than the right. Well, it is not by accident. No, it was intentionally designed in this fashion and here is why.
The sweeper with its curb brush always sweeps on the right of any isle, street or parking area. As one would be driving on the right of the road. However, in a factory setting, the isle is smaller and the need for a very tight or sharp left turn radius is a strict requirement for any sweeper.
You then might ask, How do you design such a vehicle. It is really very simple. Just offset the tire by 2 to 3 inches to the right instead of the tire being directly in the center of the machine.
While we are on the topic, there was one person who wanted instructions on how to adjust the steering/turning radius. On the Model 800 Tennant the steering is power steering by hydraulic. There is an orbital motor under the steering wheel shaft. Then hydraulic hose are tied into the steering cylinder from the auxiliary hydraulic pump. This is straight hydraulics with no adjustment. And the radius can not be changed or adjusted in any way or manner.
When explained that there were no adjustment he got upset because he wanted the sweeper to turn sharper to the right instead.
So, anyway, many machines are designed in this same fashion. Just off hand the American Lincoln 7760 Scrubber, Advance 4600 Sweeper, Power Boss TSS95 Sweeper/Scrubber to name a few.
There are, however, always exceptions to the rule. The Nilfisk-Advance 2042, Tennant 515, Power Boss 3800 all have one steer wheel in the front, exactly as a child’s tricycle. They do this because, well, that’s another story, isn’t it…
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