RC4WD Excavator

[9W Monighan]

Nice video Joe, You manage to make that operate very smoothly. What comes to mind with the motor straining is the pressure relief valve is set too high or there's a restriction on the return line? I notice it cycling slowly and that could either be too small GPM pump or a restriction. The noise, air cavitation? On my pressure washer I'm experiencing a similar problem,possibly the relief valve sticking due to rust particles getting caught inline. I have no experience with these model hydraulics but hope someday to graduate into one.

[Papy]

Originally Posted by Lil Giants

.....Papy, I did not know Leimbach had this recommendation for "break-in" (probably the word you're looking for?). But I did use a 7.2v batt during 1st time start up to fill the Leimbach hyd system to keep the oil foaming/air bubbles to a minimum while cycling the cylinders.....

Break-in....yes ! Thanks ! could not remember at the time I wrote my message

This recommendation was not written in any operating manual. I read something about that on a german forum and then asked directly to Leimbach about this process.
Doing that, I have been able to operate [intensively ] a Leimbach pump at 18 bars (260 psi) for ten years before it breaks.

Using a 7.2 V battery for a while may produce the same effect.........

[steamer]

Joe. The excavator looks great and I'm glad see the first one in use. This pump trouble your having is from lack of amperage to the motor. Brushless motors are power hogs and realy don't care so much about voltage but require lots of amps. The esc on that thing will handle 125 amp and the max you can carry on 14 Ga. wire is 15 so it's starving the motor big time. If you really want to see it perform try using a set of jumper cables and you'll be able to dig in solid rock. The info for the model looks like it needs a 6500 ma 11.1 volt lipo battery. Just trying to help before you may hurt the motor.
Rob

[doodlebug]

Hey Joe, you are way ahead of me on radio's now! Still learning.

Rob, thank's for the short lesson on brushless motor's, No idea about those at all. Gotta get past the standard rs 540 motor's, LOL!

I'm looking forward to finding out the pro's & con's of the HK hoe. Thank's for sharing!
Later, Neil#2 aka doodlebug.

[CustomRCmodels]

Wow Joe ,
You are cooking 14 ga wire with that beast ?
That is some serious amp-draw for a R/C model !
A 14 ga wire carries safe up to 30 amps ( not just 15 )
A 12 gauge wire is rated for about 40 amps
But no matter 20/30 or 40 amps , you are here in a range of a “nuclear meltdown”
If you create a short ! you better watch out handling these kind a loads !
If that included ESC is rated for 125 amps I would guess that the motor pulls like 50 amps , which would explain your wire-cooking .
Also explains why they recommend a 6500mah battery ,
( which would last only for about 15 minutes if that motor really pulls 50 amps )
that is some serious power , **** you could jump-start a real car with that !
You usually only find this in serious R/C racing .
If you don’t have an amp meter do this :
Instead using a car-battery , which supplies some serious amp-rating ,
Use a few of your NI-CD or NI-MH batteries , wire them in parallel to get a higher amp-rating and then measure the time you can run that beast .
Example : 4x 2000 mah batterys = 8000 mah capacity ,
you are running for 20 minutes = 8000:20=4000mah= 40 amps !

about the wire-cooking and amp-rating , the wire-length is also a factor ,
that’s why in serious R/C racing you keep all your wiring as short as possible ,
since in most cases the wire-size is actually undersized for the actual amp-draw of the motors.

You should use some fuses in your wiring for all this testing .
You could use some ordinary house-wring fuses .
Best would be the standard automatic fuses , the once you can reset , or also called circuit breakers. Start out with a 16 or 20 amp and if it pops right away get the next bigger one .
That would be also a simple way of testing the actual amp-draw .

I just looked at the specs of that motor ( after I already typed all the above )

· Rotational speed: 380 (kv) RPM/volt
· Input voltage: 11.1-29.6V
· Max efficiency: 98%
· Custom cut shaft or Earth Digger
· Continous current: 80A
· Warrenty period: 30 days

That is one weird designed brushless motor !
Amp-draw 80 amps , but only 380 rpm’s per volt ? at 12 volt that would be about 4500/rpms ….??? but an 960 Watt motor ( at 12 volts ) ??
A higher rpm motor with a gear-reduction would be here a much more efficient setup .
Assuming that these above motor specs are correct

What rpm motors do the other guys supply ? like Stahl and Leimbach

Makes me almost get one of these beasts and check it all out , lol

[Espeefan]

10 gauge wire would be a safer bet for 30 amps continous draw. Yes, some smaller sized wires can handle current spikes, (like motor start up) but it's not intended for continuous draw. 12 gauge wire is normally considered safe for 20 amps, but I see the bigger concern here being the fact that the tethered wire, from the power supply, is long. With 14 gauge wire, and a long run length, the motor is starved for power. 14 gauge is maybe good for 15 amps, but normally, more like 10 amps. The longer the wire run, the more resistance and voltage and current drop you have.

I have a hard time believing the brushless motor draws 80 amps continuous. That is quite an unreasonable amount of current to just turn a pump. A 6500 mili-amp pack would be dead in less then 5 mins, not to mention the battery would probably be destroyed. The motor might very well be rated to run at up to 80 amps continuous, but it probably does not. More likely that marketing likes to use that as a measure of power, saying their motor is pretty hot stuff, compared to what else is out there.

380 Kv is not so odd. It's an out-runner motor (the can spins with the motor shaft), and they typically run lower RPMs, but are better known for their torque and power, vs. an in-runner design.

[CustomRCmodels]

Originally Posted by CustomRCmodels

............explains why they recommend a 6500mah battery ,
( which would last only for about 8minutes if that motor really pulls 50 amps )
( 6.5 x 60 / 50 = 7.8 ) ...............................
Use a few of your NI-CD or NI-MH batteries , wire them in parallel to get a higher amp-rating and then measure the time you can run that beast .
Example : 4x 2000 mah batterys = 8000 mah capacity ,
you are running for 20 minutes = 8 x 60 / 20 = 24 amps !

sorry guys , had a little glitch here in my numbers this morning

[CustomRCmodels]

Originally Posted by Espeefan

10 gauge wire would be a safer bet for 30 amps continous draw. Yes, some smaller sized wires can handle current spikes, (like motor start up) but it's not intended for continuous draw. 12 gauge wire is normally considered safe for 20 amps, but I see the bigger concern here being the fact that the tethered wire, from the power supply, is long. With 14 gauge wire, and a long run length, the motor is starved for power. 14 gauge is maybe good for 15 amps, but normally, more like 10 amps. The longer the wire run, the more resistance and voltage and current drop you have.

I have a hard time believing the brushless motor draws 80 amps continuous. That is quite an unreasonable amount of current to just turn a pump. A 6500 mili-amp pack would be dead in less then 5 mins, not to mention the battery would probably be destroyed. The motor might very well be rated to run at up to 80 amps continuous, but it probably does not. More likely that marketing likes to use that as a measure of power, saying their motor is pretty hot stuff, compared to what else is out there.

380 Kv is not so odd. It's an out-runner motor (the can spins with the motor shaft), and they typically run lower RPMs, but are better known for their torque and power, vs. an in-runner design.

yes sure , outrunner , but that darn low rpm's ?
and yes about the marketing , something can't be right with these numbers , besides the fact that it's pulling current like **** if Joe uses 14 gauge wire to heat his backyard .

[Espeefan]

Yes, but look at the input voltage. 11.1-29.6 volts. That's pretty normal for an out-runner designed for airplanes or helis. They swing a pretty big prop, or spin the rotor head, usually on 6S Lipo packs. And that's not a small helicopter model either. Almost a .50 nitro sized bird. No doubt that's where the 80 amp current rating comes from. My guess is they sized the motor wrong for the application. At 11.1 volts, the motor isn't at it's most efficient operation, and it's doggy. Probably running less RPM then the Vario out-runner pump motor, at the same voltage.

[CustomRCmodels]

Originally Posted by Espeefan

...My guess is they sized the motor wrong for the application. At 11.1 volts, the motor isn't at it's most efficient operation, and it's doggy. ......

Yes , totally agree with that . Isn’t that dumb , by all these choices of brushless motors they pick that one ? But that would be the only explanation for this weird setup .
Different motor definitely would be the right way to go .
Maybe Joe should install some Heli-blades and send this in to RC4WD as an recommendation for an upgrade / conversion , Lol

Found this link here on a German forum , ( with photos )
http://www.modelltruckforum.com/index.php?page=Thread&threadID=24282&pageNo=2&high light=earth+digger
But so far no posts about any issues or this power/motor/battery question ,
just the usual bla-bla about a new toy …..

There is a Hong Kong seller selling them on German ebay ,
Sold a few and some wrote feedbacks , one also complaint about not enough hydraulic oil , wonder if he experienced the same leaking like Joe .

Searched around some and a little surprised not to find more threads on this model ..??.....

[Lil Giants]

I don't think there is anything wrong with the motor/pump Scott, I'm starting to think that this choice of brushless motor is to coincide with 3s lipo with a nominal voltage less than 12 most of the time.

And you're right as well Steve, the pressure is set much too high! If I hook anything solid with the bucket while drawing the stick towards the cab, the whole model will slide forward instantly without hesitation. This model doesn't have the gvw to handle that kind pressure. I haven't monkeyed with the pressure relief yet, not alot of time for play this wk thus far.

I don't know how using jumper cables would be of any benifit Rob? it's 14ga wire coming out of the esc.

Nathan, Willy; all good info, thanx.

It was the 18ga power cord that was cooking and that happened very quickly after increasing the EPA from 23% to 30% (increased motor rpm). Having the EPA even at 25% was making the 14ga wire warm. Currently I have it set to 20% and that seems to make the pump run plenty fast & the 14ga wire remains cool.

I have an inline fuse on this power cord with a 20amp rating, it never blew with the 18ga, but the plastic housing got so hot that it started to melt & broke connection with the model. I shut the pump off & held the inline fuse holder by hand to keep its shape till it cooled. It still works.

I used the model for a few hrs intermediantly this morning, it worked fine with the 20% EPA on the car battery.

Perhaps on Sunday I'll have some time to figure out how to implement a press guage to see what its really putting out & then adjust it lower for a more feasible operating manor.

Currently, once the pump runs for a minute or so, the flow volume gets pretty quick and makes the hoe somewhat jerky to operate b/c the cyls cylce so quick! Definitely need less pressure. The way it's set might be fine for 3s lipo, but much too high for 13v car battery.

[paul1980]

Looking forward to hearing more about this model as ive been waiting for somthing around this price range for a long time.

[Lil Giants]

Thank you for your kind words Dustin, I'll try my best to accurately inform on this model. So far I like what I see... here shortly, I'm gonna tinker with the pressure to lower it for better performance.

I don't have a scale to weight it... I used a block & a board as a balance beam, putting my Stahl equally on the other side, as I already know it's 22lbs & some... the HK hoe tip the beam easily, so I'd guess its 30lbs+.

And I'm not real clear on what measurement you're asking... I measured from the idlers (cab facing the idlers) to the back of the counterweight = 430mm

I don't know how a Bruder hoe's body would compare with either model, never seen one in person.

[trucker n]

so joe so far would you say it is a good machine for the money iknow it is early days im just thinking of getting one or a track loader just cant decide

[elliot330]

Originally Posted by Lil Giants

Joe, just how many excavators you got?

I can count 5 in this picture, two more and you'll have one for every day of the week!

I'm only jealous!

Elliot

[Lil Giants]

The Stahl Liebherr (lower left), I was using it a month ago & the lower boom broke in half. The Stahl Cat (right), the 1st ever hoe I had is eleven yrs old, the pump/valves & undercarriage continue to work work properly, but everything else is pretty well shot! I haven't use it in ... a yr or more? I've gotten my money's worth out of those two and now I'm working on wearing out these other three in the coming yrs.

[doodlebug]

Hey Joe, I watched rc4wd's video on youtube the other day, and there pump sound's a lot mellower, like it's turned down. Anybody else noticed that???????
Later, Neil#2 aka doodlebug

http://www.youtube.com/watch?v=NBy2Y...layer_embedded

[arh_3000]

Looking forward to more feedback from this excavator as the price is very resonable

[elliot330]

Originally Posted by Lil Giants

now I'm working on wearing out these other three in the coming yrs.

Good lad... don't forget to keep the videos rolling in..

With the super brights on the RC4WD 360, you could use these to illuminate the basement when videoing other equipment!

Keep up the good work Joe.

[Lil Giants]

Sounds about the same to me Neil... although some of the differences could be that that vid is outside, the camera could be quite a ways away from the model & perhaps the mic on my camera is just more sensitive. And also, I'm running my pump on 13.5v car batt, whereas that one is likely 3s lipo @10.5 to 12.6v, making the motor rpm slower -sounds softer.

My pump runs alot smoother many minutes after initial start up... the vid in the basement, that was pretty much the 1st couple minutes of my use with it ever. Now, when I start the pump out cold, I raise the tx's EPA to 22 or 23%. By one, maybe two trk loads later, I have it set back to 19% & that's where I continue use it at... seems to be the right amount of speed & power for me.

I tinkered with the relief valve, didn't have the correct fittings to tie my guage into the system however, so I don't know exactly where I'm at, but it's definitely lower than it was. Its still a bit high though. The pressure relief on this is rather mickey mouse... its a large, free moving allen screw with a short, 1/4 inch long, very stiff coil spring! Just guessing here, with just a very minute turn of the allen screw, the pressure could jump 5-10bar -> the spring is that stiff! I need to do some shopping around for a compression spring of similar diameter, but much softer tension so I can get a much finer resolution with the presure setting.

Yeah, the lights are pretty bright on this hoe Elliot. I thought the basement vid looked pretty cool using the lights... and the basement lights were on too! More vids to come later... kinda busy right now & getting busier everyday.