Designing a Heavyweight

[Anttazz]

The detail is your downfall here. Keep it nice and vague and do as little research as possible to get in there first

[supernova]

I'm not sure what you mean Anttazz...?

Do you think these pumps would work n a HW? they are 1CC/rev, and 2Kw

http://www.ebay.co.uk/itm/hydraulic-...vip=true&rt=nc

[RogueTwoRobots]

Think he was referring to me there. I spent so much time looking for the right YouTube videos that people had already posted replies by the time I'd replied and was therefore just repeating what had been said

[Eventorizon]

While we are on the subject of HW's, what ESC would you use to control the massive Ampflow A40-300's? [Link: http://www.robotmarketplace.com/products/0-A40-300.html
I would be over volting the 24V them to 36V, possibly even 48V if people think the motors can cope. First thought is a Dual channel RoboteQ of some kind, but what ampage is suitable? The motors say 340A stall but you never want to give them that power else they will just burn out, so is it best to go with the 150A Dual or can you save a bit of money and go with the 120A version?
[Link 120A: http://www.robotmarketplace.com/prod...Q-HDC2472.html
[Link 150A: http://www.robotmarketplace.com/prod...Q-HDC2450.html

[Rapidrory]

Remember that when you overvolt you're also supplying them with more current (V/R = I), so those stall current ratings will go up proportionally. If you have a controller with adjustable current limiting then you can limit it to around 150A as you say, which is well above the peak efficiency of those motors (around 40A) and still gives you about 3.5KW output power max (assuming ~70% efficiency at that power). Although, never having used a controller with current limiting, I can't say how effective it is at stopping controllers/ motors from blowing up; sudden changes in direction create current spikes larger than the stall rating, and I don't know if current limiting would react fast enough to prevent these..
The safest bet is obviously to go for a controller that can handle at least the stall current of the motor, if not more to avoid the current spikes from heavy driving (something like a Wotty, or a custom IGBT setup), however that's clearly more expensive..

[supernova]

Thor is using those ampflow motors with a roboteq 150A controller at 30V. Seemed pretty powerful at Guildford, and he has never had any issues with the controller. All very expensive though.

Back to Hydraulics, are most pumps reversible, ie if I had a pump connected to a actuator, reversed the polarity on the motor driving the pump, the actuator piston would move in the opposite direction?

[maddox10]

Most pumps are not reversible. It's only those small hydraulic "groups" that are.

If you try to reverse a normal gearpump, it will blow the seals and leak oil everywere.

[supernova]

Would it be possible to reverse the flow by using a special valve?

[RogueTwoRobots]

The hydraulic motor/pump units for sale from Kenny, linked to a few posts ago, are reversible. You just connect a couple of hoses to your ram, wire up an ESC and away you go. The Big Nipper team were slamming theirs (with brushless motor attached) back and forth several times over a couple of minutes at the the FW Champs to bleed the system through.

[maddox10]

Nothing special to a 4/2 hydraulic valve. It's even rather standard.

[Eventorizon]

RoboteQ do a single channel 300A ESC: http://www.robotmarketplace.com/prod...-VDC2450S.html , that would almost be able to deal a fully stalled Ampflow, and should be able to deal with any current spikes, shame they are so damn expensive.

[Rapidrory]

Just buy 4 of these, plug in a driver board and you've got a fairly indestructable 2 channel controller :P

[Rapidrory]

Or these ... they look like fun..

[Max]

Or these ... they look like fun..

Wow that is a good find, so you'd just need 2 of them and then 2 relays of some sort to complete an H-bridge, some sort of microcontroller and you have an esc? Though for that price it's probabably cheaper to use 4 of them using 2 just as on/off relays.

[overkill]

RoboteQ do a single channel 300A ESC: http://www.robotmarketplace.com/prod...-VDC2450S.html , that would almost be able to deal a fully stalled Ampflow, and should be able to deal with any current spikes, shame they are so damn expensive.

Remember that all the higher powered Ampflow motors have four poles, so you can use two smaller ESCs on a motor to get a larger combined current (possibly for less money too). Sewer Snake has been doing that for years and I use the same idea in my FW spinner Scissorhands.