Traction Hobby B-G550

The kind of vehicle the maker sells it as. It sets what the car is built to do and which cars it is fair to compare it with.

• Crawlers are built for slow, controlled climbing over rocks: very low gearing, flexible suspension and locked axles.

All four wheels are driven. That gives more grip under power, especially on loose ground.

• The cost is more parts to maintain.
• A crawler needs every wheel pulling to climb.

A brushed motor carries current through carbon brushes that rub on the commutator.

• It is cheaper and smooth at low speed.
• The brushes wear and the motor loses power over time.
• That low-speed smoothness is why so many crawlers use one.

Ready to run: built at the factory with the electronics installed.

• Some come without a battery or charger; the maker's box contents say which.

The maker's nominal size compared with a full-size vehicle. It works more as a class label than a measurement.

• A 1/10 monster truck is far bigger than a 1/10 touring car, so compare length and weight for real size.

The maker's product number for this exact version.

• A V2, a new color, or a kit instead of an RTR usually has a different number, and parts can differ between them.
• Check it against your box or receipt before ordering parts.

The small gear on the motor shaft. Fewer teeth gear the car shorter: quicker acceleration, lower top speed and a cooler motor. More teeth do the opposite.

• On this car one tooth changes the gearing by about 7.1%.
• Crawlers run small pinions for slow, precise wheel speed on climbs; a bigger one is quicker on the trail but harder to control on rocks.

The large gear the pinion drives. A bigger spur with the same pinion gears the car shorter.

• Pinion and spur must have the same pitch, or tooth size, to mesh.

Every reduction after the spur, multiplied together: transmission, transfer case and axle gears.

• That chain is why a crawler's figure is much higher than other classes'.
• It is fixed by the design; the gearing you change is the pinion and spur.

How many times the motor turns for one turn of the wheels. A higher number is shorter gearing: more acceleration and pulling power, less top speed.

• Crawlers run far higher ratios than other classes, so the truck can creep and hold on a climb.

The outside diameter of the mounted tire, tread to tread. A taller tire covers more ground each turn, which gears the car taller.

• Crawler wheels are named by rim size, such as 1.9 or 2.2 inches; that is the wheel, not this tire diameter.

The size printed for this link in the exact-model maker parts list.

• The listed length describes the part, not necessarily the distance between the installed rod-end pivots. Measure the assembled link before ordering a different style of replacement.

The size printed for this link in the exact-model maker parts list.

• The listed length describes the part, not necessarily the distance between the installed rod-end pivots. Measure the assembled link before ordering a different style of replacement.

The size printed for this link in the exact-model maker parts list.

• The listed length describes the part, not necessarily the distance between the installed rod-end pivots. Measure the assembled link before ordering a different style of replacement.

The size printed for this link in the exact-model maker parts list.

• The listed length describes the part, not necessarily the distance between the installed rod-end pivots. Measure the assembled link before ordering a different style of replacement.

The size printed for this link in the exact-model maker parts list.

• The listed length describes the part, not necessarily the distance between the installed rod-end pivots. Measure the assembled link before ordering a different style of replacement.

Brushed motors are commonly described by can size and turns. No motor KV is published for this vehicle; turns alone cannot supply an exact value.

The highest LiPo cell count the maker rates the electronics for. Each cell is 3.7 V nominal and 4.2 V fully charged.

• 4S is 14.8 V nominal and 16.8 V off the charger.
• Running more cells than this risks the ESC and motor.
• Many cars also run on fewer cells, only slower.

The motor fitted at the factory, as the maker names it.

• Brushed motors are often named by can size, such as 540 or 550, and by turns: fewer turns is faster.

The electronic speed control. It feeds power from the battery to the motor as you work the throttle, and usually powers the receiver and servo too.

• An amp figure in its name is normally the maker's continuous rating.
• A brushed ESC cannot run a brushless motor.
• Crawler ESCs usually have a strong drag brake, which holds the truck still on a slope when you let off the throttle.
• Set its low-voltage cutoff for LiPo, so a pack is not run flat.

The size of the stock motor's can, as the maker names it.

• 775 is a standard can size; a larger number is a longer can with more torque.

The stock servo that steers the car.

The size printed for this link in the exact-model maker parts list.

• The listed length describes the part, not necessarily the distance between the installed rod-end pivots. Measure the assembled link before ordering a different style of replacement.

Theoretical top speed is unavailable because motor KV, stock tire outside diameter and complete final drive ratio are missing.

• Enter the missing inputs in the calculator to work out a theoretical speed.