How to calculate the force on sliders?

  • #1
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Main Question or Discussion Point

hello I am trying to calculate the force applied on the sliders in that sketch
it is a level wind system for winch
I am not an engineer but as much as i understend
the 1000kg load is 10000kn becose it is 1m from the top slider
the sliders at te top are 20 cm apert so the load will be 50000 kn on the slider if it was only slider at the top
but i dont know how the load ditrubot to the bottom sliders and betwen them
ill be very thenkful if somone can explain it to me in simpel way or add link to videos in that sobject
thanks





upload_2018-8-22_11-28-36.png
 

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  • #2
.Scott
Homework Helper
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It's a little unclear how that load is being applied. 1000Kg represents a mass, which would normally present a downward force. But you have it in an arrow pointing to the left.
So one of these things are happening:
The olive colored part of the slider is being accelerate to the right of left while carrying that load. But you have not specified any such acceleration or movement.
Either left is the downward direction, or force of a 1000Kg mass in 1G of gravity is being applied to the top of the slider in the direction indicated.

You need to tell us which. In the meantime, I will assume the latter: 10,000KN of force is applied in direction indicated by the arrow.

At this point you will need to label your parts. I am going to call the four green wheel Wa and Wb (incontact with the top slide bar and the sprocket) and Wc and Wd (in contact with the lower slide bar) - with Wa and Wc on the left and Wb and Wd on the right.

Let the horizontal axis be the x-axis and vertical the y-axis. So your 10MN force is (-10,0)MN.
The olive colored bar is resisting this force through its contact with Wb (which can apply force in both x and y) and Wc (which can apply force along the y-axis only).

But to continue the analysis, you will need to specify:
the thickness of the top brown slide bar
the diameter of the green wheels.

----
Also: At this point you need to start showing us some more of your own effort on analyzing this.
 
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  • #3
.Scott
Homework Helper
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Looking more carefully at your comments, it appears that the thickness of those brown bars must be 1cm.
It also appears that you need to know two things:
1) The forces on Wa, Wb, Wc, and Wd when the only force being applied is through gravity applied to the load.
2) The forces on Wa, Wb, Wc, and Wd when the only force being applied is through the purple sprocket and the inertia of the load.

The wheel size is still critical. Looks to be about 12cm.
 
  • #4
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upload_2018-8-27_15-0-47.png









thank you for your help
for the calculation the distance from the center of wb to the top of the olive part is 1m
I add the size of the wheels
and the force is a result of the rack and pinion pushing against a cable that blocks the olive part in the right side
i add sum calculation that i learn in youtube but :
i don't know how to take in consideration the force of rack and pinion (i have to add it again or not)
and i am not sure that i am in the right direction at all with that calculation
thank you very much
alik
 

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  • #5
JBA
Science Advisor
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When analyzing the resulting reactions from the load you can simply discard the upper left and lower right wheels because all of the load vertical moment will be carried by the upper right and lower left two diagonal wheels. Approximately 1656 kg of horizontal loading will be experienced by the pinon gear with it effectively acting as the pivot for vertical forces on the two affected wheels; each of which, will experience approximately 4714 kg vertical loading on their axles and resulting in an approximate 9428 kg separating force between the upper and lower guide rails due to the load moment, . In addition, the unit's weight load, which is divided equally between the bottom two wheels, must be added to the lower left wheel load given above. The values given are close to the actual loadings but I use the term approximate because the limited dimensions given in the diagrams prevents a completely accurate analysis. The toque experienced by the pinion shaft depends upon the radius of the pinion gear.
 
  • #6
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Thank you so much
Can you please tell me what should I search for to learn more about it and to know how to calculate things like this?
Statics?
Any specific subject?
Thank you again
Alik
 
  • #7
jrmichler
Science Advisor
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Use search term statics. One of the first hits is https://www.engineer4free.com/statics.html. I took a quick look at that site, and it looks pretty good. They do state that: The lessons build on each other so we recommend that you start at the top of the list and watch them all in order. They are not kidding. You need to start at the beginning, and watch each video in order. By the time you finish, you will easily be able to find the forces on your mechanism.
 
  • #8
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Thank you very much
 

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