[TC10] Pneumatic Scissor Lift Cart

[lindr6]

Introduction:

For this contest, I wanted to model a piece of hydraulic equipment that uses a manual pumping action to manipulate the hydraulics. This would give the Technic model a natural look and feel when using the manual hand pump to activate the pneumatic cylinder(s). After much thought and searching, I landed on a hydraulic scissor lift cart. This piece of equipment will require the three main components of the Technic pneumatics system, should be compact requiring interesting mechanisms utilizing the pneumatics, and has a added bonus of being something that is rarely modeled (are there any others?) hopefully making this contest entry slightly unique!

Here are some pictures I will use for my inspiration:

Plan:

I plan to break this model into four distinct builds:

1. General Frame, including caster wheels and handle bar for pushing cart.
2. Scissor lift mechanism to raise and lower the cart table using a pneumatic cylinder.
3. Foot pump mechanism that uses the manual pneumatic hand pump to cause the pneumatic cylinder to extract.
4. Hand brake lever mechanism that moves the pneumatic switch to cause the pneumatic cylinder to retract (based on gravity, not air pressure).

Anticipated Challenges:

1. Keeping the mechanics of all the pneumatics into a low profile so that the cart table is a low as possible when all the way down.
2. The sliding mechanism of the scissor lift. I am not sure how to best model this and keep everything stable and strong.
3. Translating the vertical foot pump action to a horizontal stroke that is strong and long enough to depress the pneumatic hand pump while keeping it low profile.
4. Operating the pneumatic switch located in the cart base via a lever on the handle bar. I am currently thinking that this might be good use of the flex system! Issue here will be having enough travel to successfully move the switch far enough. Also need the mechanism to include a spring to return the lever back to initial position.

Build:

Part 1: General Frame

Here is my initial prototype to set a standard for size and to use as a base for the different mechanisms.

Part 2: Scissor Mechanism

Part 3: Foot Pump Mechanism

Part 3: Hand Lever Mechanism

Final Model:

Video:

 

Edited October 28, 2016 by lindr6

[2LegoOrNot2Lego...]

Cool! Love the way you introduce and explain this project...good luck building it! Nice start...

A site note: aren't the wheels a little to small? I think so...

[Imanol BB]

This is a pretty interesting project, is the first scissor lift car i have seen, and it looks good so far.

[lindr6]

I believe I have the basics of the scissor mechanism working with the pneumatic cylinder. I went ahead and integrated it with the frame since it really needed to be part of it to accommodate the sliding action as the lift goes up and down. Luckily, there is still plenty of room for the other mechanisms, so hopefully I can make them all fit without too much issue. The space below the table is a little thicker than I would like, as I was hoping to keep all the mechanisms below the table down to four studs, and I currently have five. I'm going to leave it as for now and can work to reduce it if possible at the end. In the real thing, there is quite a bit of space used for the mechanisms below the table, so I really do not think I am far off.

Here are some pics of the progress:

[lindr6]

Here is the mechanism I came up with to depress the pneumatic pump with a "foot pedal". This was not easy to come up with a design that has enough stroke to full depress the pump via a rotational "foot pedal" action. Also, want to keep the design to 4(ish) studs in height. Width is also important so that it will fit between the cylinder and the scissor mechanism, which gives it only 2.5 studs width for most of the length of the pump. I'm still open to suggestions if anybody has a better solution to the problem. Another thing I had to consider is the strength of the mechanism, as when the cylinder is under load, it takes quite a bit of force to depress the pump. Anyways, here are the pics:

Next up is to build this mechanism into the model!

[Rockbrick]

pure genius

[lindr6]

I now have the pump mechanism integrated into the build.  I had a little issue with the hose fitting on the pump interfering with the pneumatic cylinder.  To accommodate, I had to move the pump forward a bit to make it all work out, so not a huge deal.  Anyways, here are the pics:

Next up is to build the mechanism for the hand lever to operate the pneumatic switch.

[lindr6]

Here is my design for the mechanism for lowering the table via the pneumatic switch.  The flex system cable will be routed up the handle bar and to a lever.  I will iron that out once I integrate this mechanism.  I decided to use spring to return the switch back to center and provide tension on the lever, as it seems a little more authentic than using a rubber band.  Anyways, check out the pics:

Next up is integrating this mechanism into the rest of the model.  It should fit pretty easily as I already took my size/shape limitations into consideration.

[lindr6]

Here is the model with the last mechanism integrated into it.  Overall, the mechanism works great in the model.  I was worried the hand lever would not work well, but it works perfect.  I was also pleased that gravity is enough to allow the table to lower.  I did change the handle bar up a little to better accommodate the hand lever, and make it look a little better (in my opinion).  For anyone following this thread will see, I also refactored the entire model as I found that I could optimize things a bit now that I had all the components together and saw how everything was working.  By doing this, I was able to work out the thickness of the cart to where I wanted!  Now for the pictures:

If anybody has comments/suggestions to round out this project, please share, as I plan to shoot a video in the next two or three days.

[agrof]

I would maybe try different colors (yellow, red, blue) for the desk, but not necessary.

It might seem simple compared to other entries, but considering what it is, I say: this is a perfect MOC, and one of the best in TC10.

 

[SaGo]

Just now it looks very monochromatic!

You could change the color of the platform/table to some other color.

You could use bright colored pieces for the lever and pump. Otherwise !

[Jurss]

Could be one of my favourits in TC10.

[KikoTube]

Agreed with @agrof 

Looks cool but look even better with an other colour as platform

[lindr6]

Unfortunately, the only other color I can go with based on my parts selection is yellow.  I gave it a try and do not like the looks of it.  I think I will stick with the all grey color scheme.  Thanks for the comments!

[Thirdwigg]

This is great. Such a small and simple design with clever implementation and execution. The mechanics are perfect.

I would like more color too, but if yellow and grey are your options, stick with the all grey.

[lindr6]

Here is the video:

 

[Appie]

That was very fun to watch. I like how you managed to make all the functions work like the real counterpart.

[Josephiah]

Beautifully done - particularly love the spring return and use of the flex system.

[Aris]

Cool!