Leveling a class A

We of course have those little level things (bubble level) in the coach itself that I go by. My little coach doesn't have levelers so have to use the level blocks, need one more set. "Cat One" sits like a race car about three inches down in the nose. We just do the blocks to raise that and usually keeps me from sliding out of the bed at night. Love reading this thread. Happy trails.

pigman1 wrote:

pulsar wrote:

pigman1 wrote:
For this problem my method of estimating is accurate. This is because the sine and tangent of a very small angle is almost equal to the angle itself. This is true for 2 decimal places up to about 15 degrees and to three decimal places at 10 degrees or less. If you need exact results you need to use a calculator or published tables with values out to 8 decimal places or beyond. Just a question of how exact you want and need to be.

Measure it with a micrometer, mark it with a piece of chalk and cut it with an axe. Decide how accurate YOU need to be.

At least in my second post, I tried to indicate that I have no problem with your method. (I would have liked for your original post to be clear that you were giving an approximation.)



Perhaps you should change this post to indicate that it is the radian measures of small angles that are close approximations of the sine and tangent values of those angles. That is not true for degree measure.

In degree measure, 1 is more than 57 times larger than both sin(1º) and tan(1º). (Both values are approximately 0.01745.)

Tom

Yep, but the accuracy of the approximation still holds in this case.

Darn, You had the answer by the time I found my slide rule.

pulsar wrote:

pigman1 wrote:
For this problem my method of estimating is accurate. This is because the sine and tangent of a very small angle is almost equal to the angle itself. This is true for 2 decimal places up to about 15 degrees and to three decimal places at 10 degrees or less. If you need exact results you need to use a calculator or published tables with values out to 8 decimal places or beyond. Just a question of how exact you want and need to be.

Measure it with a micrometer, mark it with a piece of chalk and cut it with an axe. Decide how accurate YOU need to be.

At least in my second post, I tried to indicate that I have no problem with your method. (I would have liked for your original post to be clear that you were giving an approximation.)

Perhaps you should change this post to indicate that it is the radian measures of small angles that are close approximations of the sine and tangent values of those angles. That is not true for degree measure.

In degree measure, 1 is more than 57 times larger than both sin(1º) and tan(1º). (Both values are approximately 0.01745.)

Tom

Yep, but the accuracy of the approximation still holds in this case.

pigman1 wrote:
For this problem my method of estimating is accurate. This is because the sine and tangent of a very small angle is almost equal to the angle itself. This is true for 2 decimal places up to about 15 degrees and to three decimal places at 10 degrees or less. If you need exact results you need to use a calculator or published tables with values out to 8 decimal places or beyond. Just a question of how exact you want and need to be.

Measure it with a micrometer, mark it with a piece of chalk and cut it with an axe. Decide how accurate YOU need to be.

At least in my second post, I tried to indicate that I have no problem with your method. (I would have liked for your original post to be clear that you were giving an approximation.)

Perhaps you should change this post to indicate that it is the radian measures of small angles that are close approximations of the sine and tangent values of those angles. That is not true for degree measure.

In degree measure, 1 is more than 57 times larger than both sin(1º) and tan(1º). (Both values are approximately 0.01745.)

Tom

This thread is hilarious!

I'm not sure the clinometer on your phone is that accurate. You might want to just stretch a line with a hanging level from the center of the hub of the front wheel. Then measure the distance from your line to the center of the hub of the rear wheel. That's your difference. Done once.

But why bother? That's what leveling jacks are for -- to level the coach. You don't need any blocks unless you are on a serious slope.

For this problem my method of estimating is accurate. This is because the sine and tangent of a very small angle is almost equal to the angle itself. This is true for 2 decimal places up to about 15 degrees and to three decimal places at 10 degrees or less. If you need exact results you need to use a calculator or published tables with values out to 8 decimal places or beyond. Just a question of how exact you want and need to be.

Measure it with a micrometer, mark it with a piece of chalk and cut it with an axe. Decide how accurate YOU need to be.

When I was very young in the early 70's, I worked with a Forest Engineer and are job was to layout new logging roads in a State Forrest. We used a clino to tell us the degree of slope. Are steepest road ever was 22%. As a rule of thumb we considered 1% to 5% as being flat.

mtofell1 wrote:
pigman1 got essentially the same answer first but with way less math :)

That's why my post was addressed to 2oldman; I was trying to give an explanation. Also, I didn't want anyone to conclude that pigman1's and now, later in the thread, wa8yxm's methods were exact. The "approximation" part of their methods, is the assumption that the "run" for a 20' incline with a slope of 1.75% is 20'. Run is a horizontal distance and, unless there is no slope at all, part of that 20' is used for "rise."

With a very small slope, as in this case, the approximations are just as good, misses by less that .001 inch. I don't think any of us would be able to detect that, even with a good level.

But, the steeper the slope, the greater the error. To give an extreme example, suppose the slope were 100% - Note: a 100% slope is not straight up, it is at 45 degrees.

The approximation method would tell you that you need is to raise the lower end 9 feet to level. In fact, you would have to raise it a little more than 14 feet to level.

Tom

hoss-n-dawgs wrote:
If the back wheels of my RV are 1.75% lower than the front wheels (Clinometer app on my cell phone). Assuming that there is 20 feet between the front and back wheels. How high would I need to raise the back wheels to level the RV? Assume that the RV is level from side to side.

Not sure what 1.75% is, been way too long since I worked with slopes.

1.75% times 20 times 12 = 1.75% times 240 = 4.2 inches, 2-3 2x planks (At 1.5 inch each) should do it.

I built stair steps for my rig The planks are the same width as the tire tread 2x"tread width".

one foot
Two foot long
And one that is 3 feet

Glued together you back or drive onto them as much as needed.