Idea. Why hasn’t anybody made a car with a rear wiper that goes side-to-side to cover the whole window, rather than pivoting in the middle and only covering a small semi circle?

Idea. Why hasn’t anybody made a car with a rear wiper that goes side-to-side to cover the whole window, rather than pivoting in the middle and only covering a small semi circle?
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Submitted January 31, 2017 at 04:35PM by AnimusFoxx
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Idea. Why hasn’t anybody made a car with a rear wiper that goes side-to-side to cover the whole window, rather than pivoting in the middle and only covering a small semi circle?

Tested an engine on the dynamometer, and came out with a backwards Otto Cycle. Wondering why.

Tested an engine on the dynamometer, and came out with a backwards Otto Cycle. Wondering why.

Hey there /r/engineering,

We recently just tested a 1 cylinder engine in our dynamometer and the results for the PV diagram came out backwards at 3600RPM. Here's a picture of our results. This is data from 0 < crank angle < 714 degrees.

I was wondering if anyone could explain what's going on here?

Submitted January 31, 2017 at 03:53PM by trooper5010
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Tested an engine on the dynamometer, and came out with a backwards Otto Cycle. Wondering why.

Making a cruise control system with a DC-motor.

Making a cruise control system with a DC-motor.

I want to control a DC-motor powered trailer to follow a person walking in front of it. The hitch between trailer and person is equipped with a linear position sensor (telescopic).

Would it make sense to calculate the speed of the person based on the displacement/time given by the sensor and use this as reference? A controller (a proportional controller comes to mind) compares the reference speed with the speed of the motor (measured with an encoder) and tries to eliminate the error by sending inputs to the motor. Basically a cruise control system if I'm not mistaken. The reason for using a telescopic position sensor in the hitch is to reduce jerk and discomfort.

This is my first control project and I would appreciate any inputs.

Submitted January 31, 2017 at 10:31AM by sjarls
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Making a cruise control system with a DC-motor.

How does someone decrease mechanism overall length (size) while keeping the same travel length in a linear direction? (sliding table saw)

How does someone decrease mechanism overall length (size) while keeping the same travel length in a linear direction? (sliding table saw)

So currently we have a table saw that rolls along long shafts that stick out far from the table, I'm trying to redesign it such that it doesn't stick out as far from the table while keeping the same linear functionality or similar length of travel

Submitted January 31, 2017 at 08:20AM by MikeyBFSU
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How does someone decrease mechanism overall length (size) while keeping the same travel length in a linear direction? (sliding table saw)

Schematic P&ID review Ideas

Schematic P&ID review Ideas

We have been using desktop computers for submittal review, and our company has finally decided to upgrade. I am just looking for helpful ideas for large scale monitors, or other helpful equipment that will aid us in drawing and submittal review. Our PC's have I7 processors, and a dedicated AMD R5 240 GPU, so I don't think that there should be any issues with most display types. 4K is probably not going to happen for multiple reasons.

So far the prevailing idea is a large monitor or wall mounted TV at each station for prints, and then a standard sized monitor for everything else. My main concerns with this will be eye fatigue, viewing angle, and general work environment while the monitor is being used (which will be ~50% of the work day is spent reviewing and commenting on project drawings). For the last few years plan review has been painful, trying to fight your way through drawings formatted for ANSI E, on a 20" computer monitor.

What are you using, what works, what doesn't? Any other ideas?

Submitted January 31, 2017 at 10:00AM by danimal300
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Schematic P&ID review Ideas