How a differential gear works (1937) [video](youtube.com) |
How a differential gear works (1937) [video](youtube.com) |
An education in how to present to a lay audience.
There's a whole series of Chevrolet films from the Jam Handy organization at the Internet Archive. "Take it Easy", "Spring Harmony" and "Shockproof" cover how auto suspensions work. "Facts on Friction", "Hydraulics" and "What stops them" explain brakes. "Head on" and "No Ghosts" - auto frames. "Water Boy" - cooling. "Free Air" - carburetor. There's more.
https://archive.org/search.php?query=creator%3A%22Handy%20%2...
Thanks a lot for sharing.
http://www.youtube.com/watch?feature=player_detailpage&v=508...
>Only engage the Eaton ELocker™ differential while the vehicle is stationary or operating at speeds of 3 mph or less with minimal wheel slippage.
This specific locker (Eaton G80) is self-engaging up to a set speed which is intended to prevent this from happening, though it has been known to occur.
>The G80 can be very effective when used within its limitations. However its very design can lead it to failure. It requires a certain amount of speed difference between both rear wheels to operate. Basically more slip than you would ever encounter going around a turn, but it will not lock at speeds above roughly 20-30mph. This it where it earned the name "gov-lock". It has a speed governor that operates off centrifugal force inside to govern locking.
When it locks, it locks hard. Imagine one tire sitting still, and suddenly being launched to a speed of 20-25mph. That takes a great deal of force and puts a lot of strain on internals. They have a tendency to break with no warning.
Page also has photos of one that has failed.
http://www.ar15.com/forums/t_1_134/1250761_g80_differential_...
The variety of differential which does not immediately lock one wheel into another is http://en.wikipedia.org/wiki/Limited-slip_differential .
Producer: Handy (Jam) Organization ☞
Sponsor: Chevrolet Division, General Motors Corporation
Probably the source of this re-encode, with significantly less artifacts, on archive.org: https://archive.org/details/Aroundth1937
☞ Named after Jam Handy: https://en.wikipedia.org/wiki/Jam_Handy
Here is a link to a youtube playlist: https://www.youtube.com/user/navyreviewer/videos?query=mecha...
It features smoothly animated and highly functional designs as well as overlaying graphics on real footage to achieve a fashion of "augmented reality". The production quality is astounding and it is amazing to think that it was produced in the 40s. The entire video is an inspiring example of conveying information.
There's another video from 1949 about 'How a Watch Works' — http://www.youtube.com/watch?v=508-rmdY4jQ
Or you can find his channel direct on https://www.youtube.com/user/webdev17/videos
The level of effort is astounding. The "support" part holding the spokes looks cast. They couldn't have possibly cast that part specifically for this video... could they?
What a great lesson for decoupling systems. I wonder what's the software equivalent in design pattern land. The facade maybe ?
The type of locker I'm more familiar with takes a different approach: the rear end is locked by default but unlocks when it needs to. e.g., going around a turn causes the outside tire to turn faster than the inside one, and the teeth in the locker are angled so the speed difference causes them to cam out and decouples one axle shaft from the diff, letting it spin independently while the inner axle shaft is under power.
I had that system in my Toyota pickup and even in 2WD, it was absolutely unstoppable offroad.
http://en.m.wikipedia.org/wiki/RAF_Bomber_Command
The wiki article gives good explanation of how bombing developed during WWII - starting as a weapon to terrible to be used (based on poor quality data); with general agreements not to kill civilians; realising that bombers were hopelessly inaccurate; changing tactics to allow bombing of civillian populations, including the (to my mind) war crimes of fire bombing.
> Bomber Command crews also suffered an extremely high casualty rate: 55,573 killed out of a total of 125,000 aircrew (a 44.4% death rate), a further 8,403 were wounded in action and 9,838 became prisoners of war.
That's pretty much "toss a coin".
