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Thread: RC Crawler Glossary of Terms

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Old 11-08-2008, 05:27 PM   #1
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Default RC Crawler Glossary of Terms

First off, I want to give credit where credit is due. This is copied from the RC Crawler special issue, Winter 2009, and typed by Nickelpimp.
If you can think of others that should be added, let me know.

1.9 A competition or scale crawler that runs on 1.9 inch wheels.

2.2 A competition or scale crawler that runs on 2.2 inch wheels. The USRCCA's most popular competition class.

Ackerman An adjustable bellcrank steering system that consists of two posts connected by a bar. This bar is also referred to as a drag link.

Articulation An axles' ability to move vertically-left wheel up, right wheel down or vice versa-relative to the chassis.

Beadlock A type of wheel; two rings are bolted together to clamp a tire bead between them and the wheel rim.

BEC Battery Eliminator circuit.

Bind "Bind" can refer to a couple of things. One is to bind a transmitter to a receiver that runs on a 2.4Ghz frequency rather than an AM or FM signal.

Binding can also be some kind of resistance in the drive train or suspension. If the joints in a drive-shaft are bent too far they can bind when trying to rotate.

Camber The angle of the wheels/tires in relation to the ground when viewed from the front and rear of the vehicle. Zero camber means that the wheels are vertical at 9 degrees (perpendicular) to the ground. With negative camber, the wheels lean inwards towards each other, and with positive camber the wheels leaning outwards and away from each other. As a rule, having slight negative camber is good, but be sure that both wheels lean at the same angle. Avoid having positive camber (wheels lean outwards away from each other).

Center of Gravity (CG) A vehicle's balance point. The higher you chassis components sit above the wheel axles, the higher your vehicle's CG. Having a high CG may promote rollover in tight turns. For the greatest stability, arrainge your vehicle's components so that it's CG is set as low as you can get it.

Clocked A word that indicates that a coponent-usually part of the drivetrain-has been rotated to provide better alignment.

Course An area on which crawlers compete; it's marked by a series of "gates" through which drivers must navigate their crawlers.

Comp Abbreviation for competition.

Constant Velocity Drive (CVD) A driveshaft with a ball-type setup that functions like a universal driveshaft. Although "CVD" is an MIP (Moore's Ideal Products) trademark, it's now commonly used to describe any driveshaft of this type.

Damping Rate The rate at which a shock is compressed and rebounds as the vehicle runs over uneven ground. Most RC kits now have shock absorbers filled with silicone fluid/oil. Without this, shocks would be too bouncy and wouldn't be of much benefit. By using shock fluid oils of different weights (viscosities) or using a different type of shock piston, or both, you can alter your cat's dampening rate to suit the terrain and your driving style.

Differential This transforms power from the input shaft to the output shaft. The differential, or "diff," is used to alter the speed of the outside wheels of a vehicle's going through a turn to rotate the faster and travel farther thatn the inside wheels. For rock crawling, most drivers lock out the diff action.

Dig A feature of the drivetrain that allows a driver to enguage only the front or rear axle while the other axle is left to freewheel or is locked. When the front axle is being driven, this is "front dig." When the rear axle is driven, it's "rear dig." Dig is used to negotiate tight turns and avoid reverse penalties.

Droop A feature of a suspension type that, when a vehicle is stationary, is fully compressed. Articulation with a droop suspension design comes from the axle dropping , or "drooping," away from the chassis.

Dual Rates A switch that regulates the transmitter control input sensitivity. This is a usefull function for many beginners, who tend to over control their vehicles.

E-clip A small metal retaining clip that resembles a washer with a section removed and is used to keep hingepins and other types of shaft in place.

ESC Electronic speed control. An ESC regulates throttle control using it's very efficient electronic components.

EPA Endpoint adjustment. A radio function that adjusts the length of a servo's throw in either direction.

Exponential Rate Servo travel that is not directly proportional to the degree of control input. A negative exponentail rate makes the control response milder around the servo's center (neutral) point, but it becomes increasingly stronger as the input approaches 100%.

Gates Two markers identify the "gates" on a crawling course. The gates may be marked by arrows on the rocks or halved tennis balls, etc., but crawlers must pass between them to continue on the course.

Glitch This is the result of the radio interference; it's a momentary lapse in signal transmission. External sources that cause glitches include overhead power lines, but consitant glitching is most likely the result of something in a vehicle such as the sort of metal-to-metal rubbing you might find with control linkages.

Inner Axle A part of the drivetrain that transfers power from the differential to the wheels.

Lexan A clear, plastic-like material that is vacuum-formed over molds to create RC bodies. They are painted on the inside so that the paint is not scratched off on the rocks.

LiPo Lithium-polymer; in RC, it's a type of battery.

Locknut A nut that has a nylon insert that grips the threads of a bolt or a shaft to prevent it from loosening. Widely used on axles and in other areas where nuts must secure but may have to be removed frequently for maintenance or repair.

mAh Abbreviation of milliamp hour; it indicates how long a power source such as a battery will operate.

Milliamp A rating for batteries; the higher the milliamp rating, the longe the battery will provide power. Currently, most RC batteries range from 1500 to 800mah (milliamp hours).

MOA Abbrevation of Motor On Axle.

NiMH Nickel-metal hydride; NiMH cells do not have "memory" but offer a slightly lower voltage than nickle-cadmium (Ni-Cd) batteries. For average enthusiasts, they need less maintenance.

Offset as in "wheel offset." Refers to a wheel's mounting hex in relation to the wheel's centerline. A larger offset provides a wider vehicle footprint (stance), and a smaller offset means a narrower footprint.

Outdrive Shafts that exit the differential on either side and transmit driveline power to the drive wheels using an axle shaft or a universal driveshaft.

Parrallel Wiring A wiring method that ensures a constant voltage and current in a circuit. Wiring two of the same batteries in parrallel will result with the same voltage but twice the capacity of a single pack.

Peak The point at which a battery no longer accepts a charge. Past this point, energy is converted to heat that is potentially hazardous and can damage your battery pack.

Peak Charger When the battery has peaked, this type of charger reverts to a maintenance charge rate that considerably decreases the liklihood that the battery will be damaged.

Pitch In RC, "pitch" refers to the size of a gear's teeth per inch of diameter a gear has. A 32-pitch pinion gear has larger teeth than a 48-pitch gear.

Series Wiring A wiring method in which batteries are wired to increase the available voltage.

Servo-Reversing A radio function that allows drivers to reverse the output of the servo. This is useful when you switch your radio system between vehicles that may have servos in different places of orientations.

Stub Shaft Also called a "stub axle" or "wheel axle," it's the drive axle that's inside the steering knuckles.

Super Class The largest class of rock crawlers recognized by the USRCCA. Vehicles usually comprise parts from th Tamiya's Super Clod Buster.

Swaybar A heavy wire that's run across either or both of the front and rear suspension arms. It is designed to keep equeal down-pressure on the left and right when going though turns. When the outside edge of the vehicle is pushed up going through a turn, the swaybar pushes down on the inside edge to keep the tires on the ground.

Turnbuckle An adjustable link with conventional threads on one end and reverse threads on the opposite end. It enables driver to adjst their vehicles without having to completely remove the link.

TVP Twin vertical plate.

Wheel Axle The part of the axle drivetrain on which a wheel is mounted.

USRCCA United States Radio Control Crawler Association.

Last edited by freetimecrawler; 01-16-2011 at 11:14 PM.
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Old 05-31-2009, 06:15 PM   #2
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Default Definition of Wheel Speed?

After burning down a good cigar searching for the definition and application of "Wheel Speed". Wheel Speed is wheel revolutions per minute.

Watching a bunch of Competion Videos and as stated in these pages, it appears that "standard wheel speed" is about an individuals walking speed, plus or minus. These videos show crawlers proceeding from one point to another at walking speed. Until it is turned up-side down or on its side. Then the wheel speed is enough for the centrifical force on the tires (the tires balloon) and with a little traction on any of the tires, the crawler can right itself without being touched! I bet you could cut wood on some of the ballooned tires shown!

When running oval - dirt oval, we use terms like gearing, final drive, and roll-out to determine how fast we need to go!

It appears that the term "wheel speed" used in the crawler part of the hobby, is an attempt to define something that does not really exist or is of any use! Except as an individual preference or option - based on nothing other than the user.

So what formula is used to determine the correct wheel speed for rock crawling?

Last edited by Rick Findley; 05-31-2009 at 06:21 PM. Reason: added text for clarification
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Old 07-15-2009, 02:10 PM   #3
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Originally Posted by Rick Findley View Post
So what formula is used to determine the correct wheel speed for rock crawling?
Motor turns, voltage used and final gear ratio would dictate the wheel speed I guess.

It's not exactly an exact science...

Typically you put your truck on the rocks and it should be able to just barely creep along and make good power to crawl over rocks. But sometimes you need wheel speed to bump the truck up an obstacle, or make a climb up a steep incline. How much? Well, it depends a lot on your truck and it's set up.

I guess there's a good starting point, like a 55 turn motor and a 3 cell lipo (very common), then you can fine tune it with a couple teeth on the pinion gear. If you still can't motor up something, drop down to a 45 turn motor.
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Old 01-16-2011, 11:27 PM   #4
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Default FAQ's


Q.What is BEC?

A. BEC= Battery Eliminator circuit
Years ago mechanical speed controls were nothing more than a resistor circuit and you had to run a seperate battery for your servos/radio. Newer ESC's use a BEC so that you can power everything from 1 battery. Not to be confused with the CC BEC

A. CC BEC = Castle creations Battery Eliminator Circuit
The higher demands of rock crawling sometimes require the use of more than the 5v and 3 amps that the average esc's BEC can deliver. The CC BEC is a device that you wire in and replaces the BEC circuit in your ESC. Though complex sounding, it is relativly easy to wire and use.

Q. Can any one shed more light on Drag Brake and its significance in crawling (like how it is set etc.).
Is it similar to LSD (limit slip Diff) or Diff locks.

A. A drag brake holds your vehicle in position, either up hill, or down, when you release the throttle.
Settings vary by ESC manufacture.

A. No, a drag brake is not similar to LSD or Diff locks.

Q. Is there a fixed definition for a "roller" chassis?

A. Most folks would consider a "roller" to have a completely assembled chassis, axles and driveline. It would be missing electronics.[/I

Q. Can you explain a couple more terms that are used a bit?

A. Geometry in RC crawling refers to the orientation of the links of a suspension design to one another and the parts that they connect (axle to chassis)

A.Triangulation is a term that is used to decribe the resemblance of a suspension design to a triangle when viewed from above or below. Link Triangulation is used to keep any unwanted axle movement at a minimum.

Q. What is S1 and S2 when referring to batteries?

A. The S refers to the cell count of a Lipo pack. 2s is a 2 cell, 3s is a 3 cell and so on.

Q. what exactly is a Berg? is it pretty much a clod?
and what does CMS and BTA stand for?

A. A berg is similar to a clod setup in that the motors are mounted directly to the axles. This is known as a motor on axle setup or MOA. However, the berg axles are metal and have more clearance under them than the older clodbuster axles.

A. CMS stands for chassis mounted steering or servo,not sure which, and BTA stands for behind the axle.

Q. What is: axle clocker?

Q. How does it work and why?

A. Its a tool used on Berg axles to properly redrill the axles which moves the motor upward for better ground clearance and traction.

Q. What is "OG" ?

A. Old Guy/Original guy, or early RCC forum member, IE: someone who's been crawling for years.

A. OG is a term that is used loosely to signify that something is "The original" of its kind, or something generally old school.

Q. How do "lockers" work?

A. Lockers replace the bevel gears in the center differential in an axle. The diff allows the wheels on either side of the axle to rotate at different speeds. This is great when cornering, but when one tire comes off the ground, the diff system sends all of the power to that wheel. This leaves you spinning one tire in the air and going nowhere fast. The locker locks both sides of an axle together. Each side turns at the same speed as the other side, and both sides always receive power. This way, any tire that is touching the ground is moving the truck forward.

Q. Brushed vs. Brushless motors in regards to R/C crawling...
how do these to 2 types of motors apply to rock crawling?

A. This should tell you what you need to know about brushed vs brushless
Why go brushless?

Q. Can someone enlighten me to what a "sportsman" build is? I have a creeper and noticed a few sportsman builds on that forum.

A. Sportsman builds usuall entail "budget" builds, meaning that you wont see a grand plus rock machine, rather under 500 ones. So you wont see a high end brushless system on one or a 200 buck steering servo. The common sportsman esc's are the rooster crawler, FX-R, CC sidewinder and the HH Torquemaster even with a basic 45 or 55 turn motor on mostly 2s or NiMh saddle packs. They dont have a dig system. This class is great if you want to start comping but need to work on your driving skills. Its also a bit more relaxed. [/I

Q. What is Clod stall

A. Clod FAQ and Directory

Q. Is there an equivalent to ROAR for Rock Crawler competitions?

[I][I]A. USRCCA United States Radio Control Crawler Association.
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Old 03-04-2011, 01:56 PM   #5
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what is cogging?
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Old 03-22-2011, 12:13 AM   #6
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Originally Posted by jetrod7024 View Post
what is cogging?
"cogging" usually refers to the jerky, ratchety type motion caused by really strong motor magnets at really slow speeds in brushed motors. Sensor-less brushless motors can do this as well at low speeds. Sensored brushless setups don't usually have this problem, they stay smooth throughout the full range of throttle.
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Old 04-04-2011, 10:09 AM   #7
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wheel offset, could someone please explain this?

theres "axial" and "berg" offset. I see wheels for sale all the time with one or the other and i cant find a good explanation as to what they actually mean.
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Old 05-25-2011, 10:38 AM   #8
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Definition of "Motor Turns" might be something helpful in this post.?.
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Old 06-30-2011, 11:27 AM   #9
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Is KOH a term or a brand? Also, what exactly does the term "Clod" refer to?

Last edited by klamp; 06-30-2011 at 11:31 AM.
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Old 06-30-2011, 12:40 PM   #10
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Originally Posted by klamp View Post
Is KOH a term or a brand?
Both. King of the Hammers is a 1:1 crawling/desert race that happens out in Johnson Valley in California.

Originally Posted by klamp View Post
Also, what exactly does the term "Clod" refer to?
The Clod (or Clodbuster) is a truck that was made by Tamiya:
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Old 06-30-2011, 12:45 PM   #11
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So what differentiates a KOH build from a rock racer or rock buggy? Just wondering, because I see KOH-specific topics and wonder if the term is interchangeable with rock racing.
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Old 06-30-2011, 12:51 PM   #12
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Originally Posted by klamp View Post
So what differentiates a KOH build from a rock racer or rock buggy? Just wondering, because I see KOH-specific topics and wonder if the term is interchangeable with rock racing.
Well, not much is different between the two, however, you will see more independent suspension rigs in the KOH race than you will in rock racing or rock crawling.
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Old 08-13-2011, 07:59 PM   #13
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What does the term CVD mean or the letters I should say. Im looking at getting high steer knuckles and the manuf. say that they wont work with CVD's. Im curious, I was going to order MIP CVD DriveShafts. Thanks for any help. Sorry such a newb question.
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Old 08-22-2011, 02:28 PM   #14
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Default What

What is FOFF ?
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Old 09-14-2011, 07:48 AM   #15
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Originally Posted by 17dean View Post
What is FOFF ?
Formula Off Road
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Old 09-14-2011, 07:52 AM   #16
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Originally Posted by AsILayDying View Post
What does the term CVD mean or the letters I should say.
Constant Velocity Drive
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Old 09-26-2011, 06:15 PM   #17
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Hi, can somebody explain to me what's worm stall, I'm tryin to figure it out but I can't find an answer. Thanks
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Old 09-26-2011, 10:26 PM   #18
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the sway bar one is wrong... the outside tire is pushed up, the sway bar also puts upward tension on the inside tire, (reducing body roll) - basically keeping the axle straight. It it pushed down on the INSIDE tire, it would Increase the body roll instead of decreasing it.
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Old 01-04-2012, 01:31 AM   #19
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Default re: RC Crawler Glossary of Terms

thanks... im new to crawling so this helps.
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Old 02-01-2012, 11:36 AM   #20
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Default re: RC Crawler Glossary of Terms

Anybody know all the differences with the two Axial SCX10 kits. The honcho and the dingo? Only thing I can find is the honcho has a longer wheelbase.
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