High Torque Servo figures?! Confused!

[Hillman666]

I'm currently trying to build my first modified monster truck. I'm going to blame Twinset for my new interest in the trucks as it was always his trucks that I was always looking at and admiring. []

So its all your fault Twinset! lol! [][8D]

Oh and Hua15's fault! Some awesome trucks in his showroom too! []

Any way, I'm at the point where I'm trying to sort out the steering and electrics. I've been looking at high torque servo's as I think it kinda makes sense as the wheels are so big. The bit I don't get is how they work out the figures for the servo's. [?] Can anyone help me make sense of all the figures they quote or can someone recommend some reasonably priced good quality servo's? [?]

[?][?][?]

[TWINSET]

Great, somebody else's missus hates me

The servos are usually quoted in two ranges;

lb/oz or Kg - the amount of force - Higher the better

Transit - the amount of time it takes for the servo to rotate the arm a set distance. usually measured in fractions of seconds, so no big worry - more important for faster cars I think

I usually buy HiTec 645 or 945 I think, they definitely usually start with a 6 or a 9

One place that usually lists all the specs is Dinball

The Hitec 5645 (was 645, typical) has 10kg/143oz torque and the 5945 has 11kg

Speeds are 60° in 0.23 sec for the 5645 and 0.16 sec for the 5945

Remember to get a decent servo saver (Kimborough 124 are good) otherwise all the power from the servo will just flex the servo saver instead of turning the wheels

Futaba also do a good one, NetsmithUK can give you the number []

As for sources, Dinball are cheap, but check they got them first - Helluva job to get your money back.

Also, drop Biggus a line, he knows of some good ones, I think via Markthebus, but I got no idea on the spec, the prices were very reasonable though

[Hillman666]

Don't worry Andy she doesn't hate you! She was trying to get me to buy your Anti-hornet when it was for sale but I just could'nt afford it at the time! [][]

She likes most of your trucks! [^]

Plus she isnt the Missus as we are not married! (or even engaged!) lol! [][]

Thanks for the info on the servo's. Think I get it now! [:I] I hope! lol! [:I]

Just gotta find some funds to buy some!

Don't think my truck will be anywhere near as good as yours but hopefully it will turn out ok. [:I][)]

[fatboyslim]

Hitec make a HS-645MG and a HS-5645MG,the 5645 is a digital servo.

http://www.hitecrcd.com/Servos/MainFrames/HP_SFS.htm= analogue hi-torq servos.

http://www.hitecrcd.com/Servos/MainFrames/digital_SFS.htm=digital servos

[TWINSET]

What's the difference exactly?

Or rather, are there conditions when a digital servo won't work?

[fatboyslim]

Errrmm,to be honest I haven't got a scooby!!

[jozza]

Digital servos adjust the length of pulses sent to the servo motor and sends at a much higher frequency to improve the speed and effeciency of the servo motor. They do take more power from the receiver batteries than analogue ones though.

See http://www.futaba-rc.com/servos/digitalservos.pdf for a good explanation of digital servos.

[jedzuki(2)]

How many amps should the BEC supply for a high torque servo?

Should 4WS always use seperate batteries for the radio?

Many thanks. []

[raemin]

Standard servo use an analog potentiometer to identify the horn position, thi sanalog device is not extreemly precise. On the contrary the horn position is numericaly determined and hence the resolution tolerance is much more thin: if the horn moves by a very slight margin the servo atempts to compensate. I personaly have hitec 625 and 5625 servo and have to say that the 5625 is only valid for ultra precise on-road conditions: the servo permanently try to find a proper "center" and the servo keeps of adjusting, even at neutral... The sound is a bit like the one produced by an ESC at low rev. As said above the numeric servos are slightly more powerfull (no big difference though) but consumes a lot.