Would appreciate suggestions for replicating small, modern hydraulics

[KH3DP]

I've been getting more and more interested in armored engineering vehicles. I've been working on CAD modeling and test prints for a scratch-built US M9 ACE and a M1150 ABV conversion (HL M1A2 Abrams). Both projects have hydraulic features that I keep getting bogged down on the best way to replicate.

Some features I've decided to skip (hydraulic suspension for M9 due to lack of space around front suspension), and some features I've decided to go with a mechanical solution (control wires for M1150 MICLIC lids and gear motor actuator for M9 ejector). However, I'm still trying to come up with solutions for raising/lowering the M1150 mine plow/dozer blade and the M9 dozer blade.

I've seen a traditional Abrams mine plow done with gear motors. I've also seen a C2 Mexas dozer blade done with some large, partially concealed cylinders (not sure if air or fluid). While both are options, I'd like to find something that has a more appropriate scale look and function if possible. Either way, I'd be interested to hear what has/hasn't worked for anyone that's tried something similar.

For the ACE, the big issue is the hydraulic cylinders on each side that raise/lower the dozer blade. These are both very visible and relatively small with a short stroke. Scaled up to 1/16, the cylinder body O.D. is only about 8mm. I've found a number of options that are readily available, but much too big. I've found an option on ebay out of China that has the right O.D., and may be able to be modified for a shorter stroke, but if my guess is right about their internals, they're going to be weak. Even with 3D printing, the dozer blade is a large portion of this vehicle.

Any suggestions would be appreciated. If I need to provide more details, please let me know.

Thank you in advance.

[Son of a gun-ner]

For you cylinders, you could try adapting small medical syringes.
Or just model an accurate looking system with your actual hydraulics hidden away.
And for whichever path you choose, make sure your tubing is NOT silicon or soft rubber of any type, it expands too much.

[Son of a gun-ner]

Also, take a look at the Lego pneumatic system, I can't remember the physical sizes off the top of my head, but you may be able to adapt them.

[Kaczor]

How about the pistons used in RC 1/14 dozers and excavators?

[Shagnifico]

Yeah I see a lot of linear servos/actuators for rc construction vehicles on eBay and Amazon and aliexpress. Also rc hydraulic pumps too.

[Sub]

Hi,
You could try a mechanical way instead of all the hastle with hydraulics, fluid, pumps, pressure etc.
You could use threaded rod and captive nuts built into the static part of the cylinder and turn the threaded rod via a small geared motor. As the nut is captive the threaded rod when turned will pull the nut down the thread and " actuate " the cylinder, no maintenance required plus threaded bar is available in numerous small diameters and cheap to buy as are small geared motors.
This is how i will be moving my plough on a build i have started when i get back around to it, the threaded rod can be hidden inside a sleave that the rod slides in.
it does work very well and has been used before.
Just an idea.
Regards.
Sub.

[Shagnifico]

Yep, you can even buy the motor with the shaft already attached. Basically it’s the guts of a linear servo.

[Shagnifico]

However.. even the high rpm linear servos will be much slower moving than hydraulic.

[KH3DP]

Thank you for all the replies.

Son of a gun-ner:
I didn't realize LEGO has so many options. Will look into those for the M1150 mine plow/dozer, but the M9 is too limited on space for anything other than electric.
Kazcor:
I've looked at some of the construction equipment Toucan Hobby has listed, but haven't seen the hydraulics separately yet. Will look some more.
Shagnifico:
I've been experimenting with some gear motor actuators I got from ebay and Amazon. The main problems so far are size and speed, especially for the M9.
Sub:
This is the direction I'm currently headed for the first version of each model.

I came across a thread from 2015 (viewtopic.php?p=159483&hilit=dozer#p159483 - third from last post) that shows a simulated cylinder using a spring and a control cable. Has anyone come across something like this? It would appear to be a good option for the M9 due to it's size and since the resistance position (down) for the blade is also it's default position.

Does anyone have any experience with these: https://www.ebay.com/itm/325359563308? I like the diameter and that they're electric, but at that size I'm guessing they use coreless micro DC motors (very light-duty).

Just for reference, here's a close-up of the left-side hydraulic cylinder for the M9 blade.

M9 Blade Hydraulic.jpg (21.61 KiB) Viewed 713 times

Thanks again for all the advice.