This is the DS1155BLHV servo. In size and shape it's similar to our other standard-size servos - but - the output shafts position has been moved slightly to allow fitting our innovative dogleg gear train (versus the conventional inline stack - more later).
For most, this doesn't matter (the spline is still a 25T standard size), but forewarned is forearmed. And if you're thinking of using it with an X-MAXX, be advised installation is no longer drop-in because the output shaft is offset about 2mm so the stock #7749 adapter won't work. This means using our special arm with bearing is not going to work without mods that are on you and beyond the scope of the description. Honestly, we'd recommend the DS930, instead of the DS1155 for that rig so don't go and say we didn't warn you, OK?
- the 25T spline of the DS1155 is slightly offset about 2mm outboard, but still 6-bolts!
Basic specs of the DS1155BLHV are 1155oz-in and 0.10sec/60° but take note; stall current at 7A. This means you must use a healthy BEC, or a separate 2S LiPo for the control electronics. This means this servo may consumes 50W under load. Trust what we're trying to explain . . . some bogus BEC won't cut it.
It's down to bog standard math because the formula P(W) = I(A) × V(V) doesn't care about the opinions of internet experts. Put another way, watts are equal to amps times volts, which dictates you must plan your power source thoughtfully. Look, we're not trying to offend you by reminding you of high school physics, but using this servo with some bullshit power delivery system will be a headache for the same reason a fire truck hooks up to the same water main at your home - but - they they use a much larger diameter fire hose to put out the fire instead of small green garden hose.
Think of servo voltage kind of like the 60psi within the water main, but delivering current (how much water comes through) is more like the difference between a solid power source for your control electronics and bogus junk suited for toy servos, capice?
Anyway, this DS1155 servo is not only our most powerful standard-size servo but has our best ideas for getting more gear area withing a standard size case. This is big deal because an inherent problem with servos for giant scale model are twofold; first, the enormous engines are vibrating the Hell out of the control linkages (feeding straight back into the gear train). This results in premature gear wear, leading straight to excess play around neutral. So larger gears reduce the working pressure at the gear surface for the same reason a larger wing results in a lower wing loading!
And second, especially important with fast heavy surface rigs like an X-MAXX (where some enjoy jumping them an astonishing 100' through the air), the issue is shock damage destroying the gears, e.g. gears may break on impact! It's a matter of forces that are much larger for a 16lb rig compared to one weighing 8lbs, understand? So larger gears helps the impact issues a lot. And no, we're not saying the gears are indestructible (mostly because we're not stupid and we also realize some would take this as a challenge) but being larger offers you a tremendous benefit.
And here's where we talk warranty because broken gears aren't a warranty item unless we see an occlusion or other material defect. Just breaking them isn't proof they failed due to inadequate materials, but proof instead you can input more force than they can withstand. Don't come whinging to us because you broke the gears with your 16 pound truck because steel gears don't just break.
Airplane people? Ignore all this, nothing to do with you because air is compressible and you're not gonna break these gears in the air in a million years!
So how large are the gears in the DS1155? This photo shows the ProModeler DS1155BLHV gears as compared to those of a good competitor's servo, the popular Savox SB-2290SG.
- Our secondary output is about as beefy as their primary - and our primary is huge!
So larger gears address the issues of wear and breakage very nicely. And note; we use steel for the same reason cars racing at NASCAR, or a high dollar Ferrari have steel gears. Steel is simply a better material for the job compared to exotics like titanium.
However the main takeaway is DS1155 gears are bigger, so they have more surface area. This means a lower working pressure at the gear face. And when two servos both have steel gears, then larger gears are going to be better at withstanding wear and impact for the same reason coach send the fullback to get two yards at the goal line instead of the halfback. This isn't a matter of opinion, it's straight up physics and bigger is better!
But there's more involved. After all, what use beefier gears if the bearings they ride in let you down? Again, let's eyeball a popular competitor. The DS1155 bearing on the left as compared to those in Savox SB-2290SG is 25% larger, rated ABEC-9, and shielded. Theirs? Sorry, they don't say.
- Our bearing is much bigger (+25%) and shielded, plus it's the best ABEC-9 quality
Since the foundation of a load is the bearing (because it shoulders the loads), then quite honestly, there's really no substitute for size - bigger is better. But take note of two other things; our bearing isn't just significantly larger but it's also sealed. Plus we're using the very highest available quality, which is ABEC-9, because our goal in making your servo isn't fretting about costs that determine whether hobby dealers and distributors can make a living, but how it holds up in your application!
Note; the Savox is widely available through Amazon for about $140, it makes
almost 700oz-in and transits in 0.135sec/60° and honestly, it's a pretty good servo. Our point in showing you how ours compares isn't to say the Savox is a bad servo, but just that we believe ours is better. So how do you select which servo is better for you? This depends on whether you're a checkers player, or if chess is more your game. Let me explain.
For example, some guys take pride in being simple. They take pride in making decisions happen fast, and because they look at the price and torque to decide, then bang, they're done! Thing is, yes, torque and price are pretty important, but that's not all that's important when making servo decisions. These are other factors to consider.
Factors affecting your purchase
For example, savvy thinkers aren't impressed by whether the servo's pretty and shiny, and they largely ignore the ravings of anonymous internet experts. Neither, do they put much stock in what those who are sponsored say because of a) a realization transmitter-skills (hand-eye coordination) don't mean what they think is important, and b) because if they're sponsored, then they're only saying what they're told to say (e.g. parroting the company line), plus c) and this is especially important, the savvy guy alone defines what's good for him, not others.
So if you always do what's best for you, then keep reading!
And extending this to chess, champs don't think one or two jumps ahead, but understands the nuance involved in considering several possible moves and out into the future! For example, he wonders; what's under the covers? After all, when you price ours versus theirs, if you didn't know why our servos cost more, then looking at what's inside, e.g. at our larger gears and bearings, you realize part of the answer. But there's more.
For example, some servo vendors resort to 12-15V to achieve these levels of torque and speed. We don't, which means this ProModeler DS1155BLHV servo has been designed for maximum compatibility. In other words, a standard 2S LiPo (or healthy BEC) is all you need. Of course, we grok those who drive 4S-powered trucks are easy to persuade that connect their steering servo to their 4S propulsion pack is convenient, but is it a good idea? Honestly, our opinion is it's beyond dumb and bordering on stupid. Strong words?
Maybe, but here's why we think savvy modelers shun this whole concept for standard class servos. When you accelerate the truck, did you realize the propulsion motor depresses the pack-voltage? And not a little bit, but a lot! Prove it yourself by putting a volt-meter in line with the pack and you'll see that even brief accelerations (put it on its back so there's no-load but the tires and wheels) easily depress a 4S battery pack from 14.8V down to 10V, or less. And it's far worse when you're accelerating a 16lb truck! Anyway, I'll bet you a milkshake the guy promoting the idea of standard size servos connected to the 4S propulsion pack doesn't mention this detail, am I right?
So look at servo performance charts. We include them for the savvy who understand what they're looking at. What immediately jumps out at you is the servo makes less power at lower voltage, right? And this is true for ALL servos, all brands. Fact of life. But it gets worse because as voltage goes lower, you not only get less torque, but you also get less speed than you paid for. Raise your hand if you believe the precise moment you're gunning the throttle, is also when you want your steering servo to produce less torque and get slower. Honestly, anybody who still believes variable servo performance is a good thing is too probably also too dumb to appreciate what ProModeler servos bring to the table. Add to which, this class of servo will consume 50W, which is an
appreciable fraction of your propulsion pack's capacity. This means shorter runs. Lose-lose.
Bottom line? When you're shopping for servos, be careful because the hucksters and snake oil salesmen are out laying in wait and they're using fools and anonymous internet experts to help promote dumb ideas!
Now for some Q&A.
Q. Will the DS1155 work in and X-MAXX?
A. Yes, and no. Yes, with an X-MAXX beam mod it will fit but no, the output shaft will not align properly with the bearing supported arm of an X-MAXX.
The reason for this is because the dogleg gear stack offsets the 25T splined output shaft of the DS1155 servo outboard from that of a conventional servo like DS630 or DS930 and competing servos from Savox, MKS, and others by about 2mm. So yes, you may use it but you're going to be on your own for a servo arm, or you're going to find a way to modify it to fit that retains the stock output shaft position. We're not saying you can't because we make it a point of never underestimating folks, but it's gonna be a lot trouble. This is why we begin by suggesting you get the DS930, instead!
Further note; once we make a beam mod for you, e.g. cut the servo beam for fitting to an X-MAXX, you cannot get a refund - it's yours. So be certain of what you're doing before trying this and don't come whinging to us about you didn't know because we're warning you . . . . right here, and now!
Q. Asaf Karas wrote; will the servo work with the Traxxas VXL-8s ESC/BEC?
A. Yes, but the important figure when reviewing their specs is the claim of BEC Continuous Current of 10A. That's plenty - but - the fly in the ointment is this is at 6V while the servo is rated at full power at 8.4V. IF you're fine with reduced performance because you only care about durability, then go ahead.
However, if you want both the high performance you pay for 'and' the durability, then either opt for a better BEC to power the servo, or run it off a 2S LiPo (as if it were a nitro powered truck). Honestly, X-MAXX are big ass trucks and finding a place to Velcro a small 2S pack isn't too tough. But if you prefer the convenience of a BEC, then the Castle Creations CC BEC Pro is also rated at 20A and in our view, is a better option than stock.
Note; we offer both. The pack will likely run the truck all day and you can use your regular charger to top it up, but whatever floats your boat is fine by us.