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| Posted: Thu Jul 25th, 2013 02:50 am |
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21st Post |
mwiz64
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That is quite a nice video, Bernd. Thanks for sharing that with me. Now ill have to go back and watch it again when I'm less prone to dozing off....
I do like those unloaders. Very cool and very interesting. Your project does seem quite ambitious but it certainly would be something to behold. Ill just stick to building one of those car pushers.... Maybe in 1:35n2.Last edited on Thu Jul 25th, 2013 01:44 pm by mwiz64
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Mike
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| Posted: Thu Jul 25th, 2013 03:59 pm |
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22nd Post |
| Posted: Thu Jul 25th, 2013 08:45 pm |
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23rd Post |
Bernd
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How about that an, automated Walthers kit. Did you notice the jerky movement in a majority of the machine? Even the pusher engine was jerky. I realize it's HO and weight is a concern, to light, but if you use high geared motors it's possible to slow down those jerky motions.
I think I'm going to enjoy making an animated one when I get to it.
Bernd
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| Posted: Thu Jul 25th, 2013 09:06 pm |
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24th Post |
Bill Fornshell
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Not to take anything away from the person who built this, but, if you were running it with radio control and battery power you could add some "momentum" to the mix and smooth the start and stop movement.
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| Posted: Fri Jul 26th, 2013 03:03 am |
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25th Post |
mwiz64
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Momentum in the typical model railroad sense is nothing more that a slow ramp up and ramp down of electric power. This supposedly makes the electric motors start up more slowly. In reality, many of them do still lurch into action when the voltage finally overcomes the friction of the drive train. With a battery powered motor controlled by an ESC this is likely to be about the same.
What deep gearing does is smooth out the lurch of the motor and reduce the effects of the friction in the drive train.Last edited on Fri Jul 26th, 2013 03:03 am by mwiz64
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Mike
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| Posted: Fri Jul 26th, 2013 03:31 am |
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26th Post |
pipopak
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mwiz64 wrote: What deep gearing does is smooth out the lurch of the motor and reduce the effects of the friction in the drive train. Deep gearing makes the motor spin faster to start moving the loco. Actually a deep gearing with MORE gears has MORE friction. If you have the physical space to put a bigger gear wheel with the smallest size pinion on the motor you will be in better shape to deal with friction. Jose.
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| Posted: Fri Jul 26th, 2013 04:18 am |
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27th Post |
mwiz64
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Try moving a motor shaft with a small gear spinning a large one some time. The motion is smoother because it takes less effort to move the large one. You don't move it as far but the mechanical advantage is huge. Will that actually reduce the friction?.... I have to think about that one a little. It certainly smooths out the bumps and clunky motor opperation.
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Mike
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| Posted: Fri Jul 26th, 2013 04:55 am |
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28th Post |
pipopak
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mwiz64 wrote: Try moving a motor shaft with a small gear spinning a large one some time. The motion is smoother because it takes less effort to move the large one. You don't move it as far but the mechanical advantage is huge. Will that actually reduce the friction?.... I have to think about that one a little. It certainly smooths out the bumps and clunky motor operation. The friction gets reduced when you use a smaller number of gears everything else being equal. Two gears molded together (one big paired with a smaller one count as two. More gears=mode friction. Note also that in relatively low precision mechanisms like the drive trains we use most of the time not only the tips of the gear teeth make contact but also the sides of the gears rub one against the other in opposing directions. This is the biggest offender. Jose.
Last edited on Fri Jul 26th, 2013 04:56 am by pipopak
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| Posted: Fri Jul 26th, 2013 07:06 am |
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29th Post |
oztrainz
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Bernd wrote:
Here's a 12 minute video. It shows them actually moving cars.
http://www.youtube.com/watch?v=JErREoMOdDc
It looks to me like it could be 2' gauge. I've also come to the conclusion they were electric powered. They must pick up the current between the tracks.
I'm thinking of building a warf unloading diorama featuring a couple of the Hulett un-loaders. I just recently ordered a Walthers kit and have prints coming for the Hulett un-loader from Bearco Marine Models. They also have HO scale boat kits. I'd like to make it all animated. Tall order I know.
Bernd
Hi Bernd & all,
I'm betting that they were 3'6" gauge rather than 2' gauge based on the fact that there was a lot on underground mining gear built to that gauge and these units seem to have significant similarities to mining locos and/or coke oven hot cars (aka quencher cars).
Looking at your video, the centre cover between the tracks actually looks like an I Beam that covered the live rails at 2:04 in. You can see the live rail under the centre cover in this video http://www.youtube.com/watch?v=1RJfnk2S330 at 1:29 in. This video also gives a whole new meaning to "riding the bucket".
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John Garaty
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| Posted: Fri Jul 26th, 2013 11:53 am |
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30th Post |
Bernd
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First a lesson on gearing. I worked for a major gear manufacturer that is known world wide. I worked with process engineers developing correct settings for machines in the field to produce the known hypoid gears used in rear wheel drive cars and then on hobbing machines that cut the spur/helical gearing for front wheel drive cars.
With that said I think it qualifies me to point this out about gearing. Spur gears almost have no friction. The teeth do not slide across surface face. They actually roll. The helical gear has a sliding effect as it transmitts power from one tooth to the next. The hypoid ring and pinion in your rear wheel drive cars has the highest friction do to a sliding motion as it transmits power from the pinion to the ring gear. And the worst for friction would be the worm and wheel.
Spur gears - http://images.yourdictionary.com/spur-gear
Helical gears - http://science.howstuffworks.com/transport/engines-equipment/gear3.htm
Hypoid gears - http://commons.wikimedia.org/wiki/File:Hypoid_gear.jpg
Worm and wheel - http://science.howstuffworks.com/transport/engines-equipment/gear5.htm
I've list the above gearing in order of friction.
Adding more gears in a spur gear reduction box will add friction on each bearing surface of the shaft, true, but the reduction gearing also creates more torque at the output shaft from a small motor running a high rpm at the input shaft.
If you have 8½ minuets watch my video on an R/C crane I modified.
http://www.youtube.com/watch?v=X-upfCtxtLY
Near the end of the video show the motions of the crane using the radio controls. The movie has been speed up by a factor of 2 so those of you that get bored won't fall asleep. All three motors used are high reduction. And I'm using one of David T's (DelTang) receivers. This was the first conversion of such a kit that I did and was not quite as smooth as I had hoped for.
That's it for my gearing lesson. Oh and the company I worked for was Gleason Works. They're on the net if you want to check them out.
@ oztrains, I've seen the video and that's on of the two the has inspired me to "want" to build a diorama depicting these monsters un-loading a ship. Thanks for the thought that they may be 3'6" gauge. Could also be 3' gauge come to think of it.
Bernd
Last edited on Fri Jul 26th, 2013 11:54 am by Bernd
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