Some dimensions would aid in analysis

Is the prototype using a large hydraulic ram or gearing for the lift? Any shots of the underside?  Links to the hoist manufacturer?  

I’d be inclined to a speedy motor and super high reduction gear ratio, hidden if necessary if the prototype uses a big ram, which could be faked with sliding brass or  styrene tubing with clearances to prevent binding.

You might want to peek at this and talk to Seth.   MP5. It’s pretty Torquey and has about a 12 mm displacement - hooked to the right kind of pivot ....  Also, The little gear in here, meshed to a big gear at the pivot...

Seth carries all sorts of cool things that might help.

Hydraulic Dump confirmed

Dear Mike,

30 sec with Google says "Hydraulic Lift Confirmed"

https://www.aminternationaltnllc.com/equipment/wood-chip-dumper/

Given the comparative featherweight load of a Styrene/3D-print bridge + plastic (PromoTex/Herpa) truck,
a high-torque servo (metal-geared HS-311?) or something heavier "stall-motor" style like a Tortoise or MicroMark Switchtender should work OK?

Happy Modelling,
Aim to Improve,
Prof Klyzlr

@Araner re: Mechanism

Hi Araner (name?),

I think this is actually fairly easy. A servo, even a really good modeling one, is not going to give you smooth motion used directly. A highly geared stepper would work but I think is un-necessary.

I suggest a screw drive using a geared motor ( https://www.ebay.com/itm/262715959029 ) coupled to a 2-56 threaded rod hidden near the pivot point in the housing. For the hydraulic ram, simply model it to scale, and have the lift assembly literally pull it up out of a hole to simulate the ram. For the screw drive the coupling can be a silicone flex tube. The guides for the screw coupling are important to absorb and minimize the vibration of the screw. Very smooth and slow motion can easily be achieved. Here's what one looks like in a different application. The coupling to the forklift was magnetic. Yours would need to be direct and mechanical.

You would not need one as long, and the coupling on the screw would be connected to the ramp holding the truck to be dumped. Reed switches or Hall effect sensors could detect the stopping points at each end. In the picture above microswitches are used to detect end points and actuate a small latching relay to reverse the motion. Click on the pic to get a higher res view.

Good luck with your project and have fun! 
Best regards,
Geoff Bunza

For a scale hydraulic ram...

Dear MRHers,

For one example of a scale hydraulic ram, check out the work of Giles B, a quietly-nuts (in a Good way) NG modeller from the UK who is doing wonderful things with gearhead motors, magnets, and RC control...

Dig into his YT channel for all manner of scale animation gems...

Happy Modelling,
Aim to Improve,
Prof Klyzlr

That Is A Striking Image

Of the Rumford mill at the top of the thread. Would appreciate more info, if possible. 

That opening photo really is amazing

Great ideas in this thread from everyone.  Professor to the rescue with all the links .  

I noticed on the product line page there are even scale  drawings

Those Gyles B videos are awesome. 

I really like the threaded rod idea - it could be hidden in the base of the ramp to preserve the illusion of the hydraulic rams — that's the only thing a bit off about Gyles' tipper truck - the hydraulic isn't really working right as it's fixed length.  A person would have to do up some drawings and experiment a bit. 
 

If the rams are made big enough, threaded rods might be hidden inside them to get the motion just right, perhaps driving two rods with large gears off one motor with a small gear to keep them synchronized, with the mechanism under the structure hidden from view.  Maybe someone makes a small gear box for a model ship to drive two propeller shafts with one motor.  Or just use something like this, replacing the prop shafts with threaded rod.  I think one motor would be better though, everything direct coupled to avoid twisting.

Boat motors.  

I am tempted to try the worm drive threaded approach on my streamtable crossing on the BH as it will be far smoother than a turnout motor.   

Even more confirmation

If you click on the picture of the chip truck being dumped and then enlarge to full size you can clearly see the two hydraulic rams one on each side of the truck. No googling needed.

If you document this animation project on your blog please let us know here when you update your blog so we can all check it out.

Thanks,

I

I wouldn't worry about the hydraulics and drive it from the pivot where the ramp attached to the ground.  The hydraulic cylinders would just be along for the ride.  A counterweight, if needed, could be inside the building.

Great suggestions!

Thank you for all the great suggestions!  I went ahead and ordered one of those N20 Geared motors that Dr.Bunza linked.  Does anyone have any suggestions for driving one of those motors off an Arduino?  In the past, I believe I connected DC motors to the screw terminals on a Motor Shield.

  As I also mentioned in my OP, I'm also planning to run a bulldozer in a forward/reverse movement.  In fact, I was basing my design off of the same magnetic forklift project geoffb posted above only I would use a physical connection and wanted to add mp3 sound modules for the forward and reverse sounds.  I was planning on using a stepper motor and threaded rod from an old 3D Printer, but perhaps a geared DC motor would be better in this case too?  Any thoughts?

@Araner re:Drving Motors with Arduinos

Hi Araner,

You can get simple on/off motor control for most any DC motor by using an Arduino pin to switch a relay like https://www.ebay.com/itm/224353581651

They are Single Pole Double Throw (SPDT) relays. Put two switched simultaneously and you have a double pole double throw (DPDT) switch that you can use as a simple reverser. If you want speed control from the Arduino, then using an H-Bridge Motor Shield will enable Pulse Width Modulation (PWM) speed control as well as give you direction control. For simple on/off control you can also use a transistor switch (like a 2N2222A).

The transistor switch and another small alternate relay are described here: SMA34 More Power to SMA20 Decoders with Tips and Additions  https://forum.mrhmag.com/post/sma34-more-power-to-sma20-decoders-with-tips-and-additions-12215355

Using DFPlayer sound modules can be found here:  A modeler’s introduction to the Arduino  in the December 2016 MRH http://mrhpub.com/2016-12-dec/online/html5/index.html?page=1&noflash  The additional article downloads have more info and an operating manual/datasheet.

Have fun! 
Best regards,
Geoff Bunza

I have used this mechanical system with success

.

In the way to build a Hight lift coal dumper, it was necessary to find a way to elevate and lowering the dumper.

Since I model in N scale it was necessary to find an invisible way.

I needed only a 2 cm travel but the device can be adapted to have more travel.

The dumper has in the two columns two rods which serve  of pusher and  push up and down the dumper.

To completely hide all the mechanism, it has been concealed under the high lift.

How it works,

I use an Hankcraft display motor; on the axle of the motor is fixed a threaded rod ( mine is 8mm diameter)

The threaded rod  run in an taped bloc which is guided by two guides; the bloc go up and down depending the way the motor is turning.

The bloc push the two rods up and down and I have my up and down movement of the bumper.

Since the two big hydraulic cylinders who push and elevate the truck are similar of my two rods may be my mechanism could be adequate for your needs

The two simulated hydraulic rods in fact go through the plywood base and the mechanism push them under the plywood base.

Course is limited by microswitch activated by the pusher bloc

I modified my basic plan to show you how it could be done.

Marc

The trouble with the above diagram is the "Truck Elevator" moves in an arc but your "Modeled Hydraulic Pusher" is restricted to a straight line.  

I'm still in favor of something similar to a windshield wiper on a car, except slower so the truck isn't launched across the room.  

@ KJD

.

It's not necessary the hydraulic cylinder are vertical; they can be be pushed in a angled plan.

I draw them perpendicular of the pusher bloc; because this is my need for the High lift

But if a hinge fix the two cylinder rod at the pusher bloc, there is no necessity to be perpendicular; the axle from the elevator point and the base of the "modeled Hydraulic cylinder can have an offset center point

This way you can push the two rod with an offset position giving the illusion of the arched movement

Since you have two hydraulic pusher you need to have a mechanism which move the two in a same way at the same speed at the same moment and similary

This was my personal challenge and the mechanism achieved the motion perfectly for the high lift, a two spaced rods which must move in the same time

This is a basic schematic with  a correction which could give a arched movement of the hydraulic pusher.

Course this need to calcul the right angle and point of fixation of the hinge on the bloc pusher

The hole in the base need to be ovoid and also drilled in an angle, but scenery can easily hide the trick.

The base of the Hydraulic cylinder can be an articulated tube where the rod elevator slide in giving the illusion it's a hydraulic cylinder

.

For the lift mechanism one

For the lift mechanism one could use a geared motor with a worm drive at the bottom hinge. The hydraulic ram would be just for. It could be a single rod or telescoping tubes.

Here is an example of the crane boom lifting mechanism of an HO-scale Liebherr LM1045 mobile crane:

And here a video of the same crane:

Regards,Volker

Re: Rumford Mill

My apologies for missing this question when you first made it.  Might I ask what info you would like to know specifically?  I switched this mill a lot in past years and occasionally still pick up trains from there.  I'd be willing to create a separate post on the subject if there's anything in particular you'd like to know.

The OP image I believe wasn't taken from me but I did take the following pic from the same vantage sometime last winter 

Consider a good ol' Tortoise switch machine...

The OP could facilitate a Tortoise switch machine with heavy gauge piano wire to lift and lower the dump platform at a prototypical speed & motion.