Motor Slot Speed Machine Slot

The original brushless DC (BLDC) motors were designed with slotted stators, and the majority of BLDC motors are still made this way. But this design produces cogging torque, which makes it difficult to achieve smooth motion, especially at slow speeds. To eliminate this effect, a new design was developed, eliminating the slots in the stator (which are the root cause of cogging torque), and slotless motors were born.

Slot car motor parts products available at Professor Motor, Inc.

In a slotted motor design, the stator is made of slotted steel laminations that are stacked together, and copper windings are inserted into these slots. (The design of the stator is sometimes referred to as having “teeth.”) The slotted motor design is simple and inexpensive to manufacture, but it has a major drawback—cogging torque. Cogging torque (also referred to as “detent torque”) is a result of the permanent magnets in the rotor attempting to line up with the slots, or teeth, of the stator. The primary effect of cogging torque is that it causes motor rotation to be jerky (not smooth), especially at low motor speeds.

The term “iron core” is commonly used when discussing slotted linear motors. This originates from the fact that the assembly of stator windings encased in a steel, slotted stator is sometimes referred to as an “iron core.” Slotless linear motors, on the other hand, are often referred to as “air core” motors.

In a slotless motor, there are no iron teeth to support the windings. Instead, the stator lamination is constructed of steel rings that are stacked together, and the windings are encapsulated in an epoxy resin, which gives the winding structure shape and rigidity. This “self-supporting” winding is placed in the air gap between the stator lamination and the rotor.

The primary benefit of a slotless motor design is that the lack of teeth in the lamination eliminates cogging torque and results in a motor with very smooth running characteristics. Torque production is predictable and highly controllable, because in the absence of these uncontrolled disturbances (i.e. cogging torque), motor torque production is directly related to the current supplied to the winding.

There are other benefits to the slotless design. First, the elimination of cogging also significantly reduces audible noise. And since there’s no iron core, inductance is very low and current can get into the stator windings very quickly, making slotless motors good for applications that require high acceleration and dynamic response.

First Slot Machine

But slotted motors still hold some advantages. For example, the air gap in a slotted motor is smaller than the air gap in a slotless design (which must accommodate the self-supported winding assembly). This means that the flux density is higher in a slotted motor, and torque production is more effective and efficient.

One way that manufacturers of slotless motors overcome the effects of the bigger air gap is to use larger, stronger permanent magnets in the rotor. But this increases cost. And, the cost to manufacturer the self-supporting winding structure is typically higher than a conventional slotted design. For this reason, the traditional slotted motor design is still the first choice for applications in which smooth running and the elimination of cogging are not critical.

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Looking to get a brushed motor for your rig, but don’t know where to start? Too many choices got you dizzy in the head? This guide will help you make a motor selection and ensure you get what you need and gear it properly!

Are you just starting out and don’t know what to get? Select a 55t TorqueMaster. 20t CrawlMaster, or 2200kv brushless for slow going and long run times or a 27t TorqueMaster, 13t CrawlMaster, or 3300/3500kv brushless for more power and wheel speed.

Motor slot speed machine slots

Don’t let your motor temperature get over 160°F (70°C) for best motor life! When in need of more speed, volt up and gear down instead of increasing the pinion size.

Purchasing for a child new to R/C crawling and trail running? The 55t TorqueMaster 540 Expert motor for crawling is our best suggestion. It is not overly powerful on 2 or 3s LiPo and is less likely to break parts. Faster (lower) turn counts, Pro series brushed motors, and brushless motors can break parts more easily. Beware of the power!

Below is a list of motor turn counts and speeds. Motors on the same line have equivalent speeds.

Motor Type3 slot straight armature3 slot skewed armature5 slot straight armature5 slot skewed armatureBrushless
Fastest4500kv
4100kv
3800kv
3500kv
3300kv
TrailMaster Sport 550 12t3100kv
CrawlMaster Pro 540 11tPuller 400 Crawl 13t
Puller 500 Crawl 11t
2700kv
CrawlMaster Sport 550 8t2300kv
Lil' Tugger 30t
TorqueMaster 540 27t
TorqueMaster 550 21t
Custom Pro 540 27t CrawlMaster Expert 540 13t
CrawlMaster Pro 540 13t
CrawlMaster Pro 550 10t
Puller 400 Crawl 16t
Puller 500 Crawl 13t
2200kv
Lil' Tugger 33t
TorqueMaster 540 30t
Puller 400 Flow 33t
Puller 500 Flow 30t
CrawlMaster Sport 540 13t
CrawlMaster Sport 550 10t
CrawlMaster Magnum 540 11t1850kv
TrailMaster Sport 540 27t
TrailMaster Sport 550 21t
1800kv
CrawlMaster Expert 540 16t
CrawlMaster Pro 540 16t
CrawlMaster Sport 550 12t
CrawlMaster Magnum 540 13t
Puller 400 Crawl 20t
Puller 500 Crawl 16t
1700kv
Lil' Tugger 38t
TorqueMaster 540 35t
TorqueMaster 550 27t
Custom Pro 540 35t
Puller 400 Flow 38t
Puller 500 Flow 35t
CrawlMaster Sport 540 16t
CrawlMaster Pro 550 12t
CrawlMaster Magnum 540 16t1500kv
CrawlMaster Sport 550 13t1450kv
TrailMaster Sport 540 35t
TrailMaster Sport 550 27t
1400kv
TorqueMaster 540 40t
TorqueMaster 550 30t
CrawlMaster 540 20t
CrawlMaster Sport 550 15t
Puller 500 Crawl 20t1250kv
TorqueMaster Magnum 540 38t1200kv
TorqueMaster 540 45t1100kv
SlowestTorqueMaster 540 55t
TrailMaster Sport 540 55t
TrailMaster Sport 550 45t
1000kv

Motor And Gearing Recommendations By Vehicle

Axial AX10

General Trail use:
35t – 27t TrailMaster Sport 540*
35t – 27t TorqueMaster 540*
16t – 13t CrawlMaster 540*
Competition:
30t – 27t TorqueMaster 540*
13t – 11t CrawlMaster 540*
*5.6:1 pinion to spur ratio advised to prevent overheating. Example: 15 tooth pinion and 84 tooth spur

Axial Capra

General Trail use:
55t – 35t TrailMaster Sport 540
55t – 35t TorqueMaster 540
20t – 16t CrawlMaster 540*
16t CrawlMaster Magnum 540
Puller Pro BL 540 Stubby or Standard
TrailMaster Pro BL 540
Revolver 540 Sensorless
*10 or 9 tooth pinion needed

Axial RR10 Bomber

General Trail use:
27t – 21t TrailMaster Sport 550*
27t – 21t TorqueMaster 550*
15t – 10t CrawlMaster 550*
Puller Pro BL 540 Standard, 540-L, 540 XL
TrailMaster Pro BL 540
*11 tooth pinion / 68 tooth spur advised for brushed motors to prevent overheating.
Stock gearing compatible with brushless motors.

Axial SCX10

Slot machines info

General Trail use:
35t – 27t TrailMaster Sport 540*
35t – 27t TorqueMaster 540*
16t – 13t CrawlMaster 540*
Puller Pro BL 540 Stubby or Standard
TrailMaster Pro BL 540
Revolver Snubnose 540 or Revolver 540 Sensorless
*5.6:1 pinion to spur ratio advised for brushed motors to prevent overheating. Example: 15 tooth pinion and 84 tooth spur
Stock gearing compatible with brushless motors.

Axial SCX10 II

General Trail use:
35t – 27t TrailMaster Sport 540
27t – 21t TrailMaster Sport 550
35t – 27t TorqueMaster 540
27t – 21t TorqueMaster 550
16t – 13t CrawlMaster 540
15t – 10t CrawlMaster 550
Puller Pro BL 540 Stubby or Standard
TrailMaster Pro BL 540
Revolver Snubnose 540 or Revolver 540 Sensorless
Stock gearing compatible with brushless and brushed motors using stock tire sizes.
Brushed motors will require gearing down if increasing wheel and tire size.

Axial SCX10 III

General Trail use:
27t – 21t TrailMaster Sport 550 (12t is not suitable for crawling)
27t – 21t TorqueMaster 550
15t – 10t CrawlMaster 550
Puller Pro BL 540 Standard
TrailMaster Pro BL 540
Revolver 540 Sensorless

Axial SMT10

General Trail use:
27t – 21t TrailMaster Sport 550
27t – 21t TorqueMaster 550
15t – 10t CrawlMaster 550
Puller Pro BL 540 Stubby or Standard
TrailMaster Pro BL 540

Axial Wraith

Motor slot speed machine slots

General Trail use:
35t – 27t TrailMaster Sport 540*
35t – 27t TorqueMaster 540*
16t – 13t CrawlMaster 540*
(the 13t TorqueMaster 540 is not suitable for the Axial Wraith)
Puller Pro BL 540 Stubby or Standard
TrailMaster Pro BL 540
*5.6:1 pinion to spur ratio (or even lower gearing) advised to prevent overheating for brushed motors. Example: 15 or 14 tooth pinion and 84 tooth spur.
Stock gearing compatible with brushless motors.

Axial XR10

General Trail use:
35t – 27t TrailMaster Sport 540
40t – 27t TorqueMaster 540
16t – 13t CrawlMaster 540
Competition:
35t – 30t TorqueMaster 540
16t – 13t CrawlMaster 540
Start with stock pinion, 14 tooth or smaller

Axial Yeti (1/10)

General Trail use:
Puller Pro BL 540 Standard, 540-L, 540 XL.
(1/8 scale Yeti XL is incompatible with our motors)

Element RC Enduro

General Trail use:
35t – 27t TrailMaster Sport 540
27t – 21t TrailMaster Sport 550
35t – 27t TorqueMaster 540
27t – 21t TorqueMaster 550
16t – 13t CrawlMaster 540
15t – 10t CrawlMaster 550
Puller Pro BL 540 Stubby or Standard
TrailMaster Pro BL 540
Revolver Snubnose 540 or Revolver 540 Sensorless

enRoute Berg

General Trail use:
40t – 27t TorqueMaster 540
16t – 13t CrawlMaster 540
Competition:
35t – 30t TorqueMaster 540
16t – 13t CrawlMaster 540
35t – 30t Puller 500 Flow
16t – 13t Puller 500 Crawl
12 tooth or smaller pinion recommended

HPI Venture

General Trail use:
35t – 27t TrailMaster Sport 540
27t – 21t TrailMaster Sport 550
35t – 27t TorqueMaster 540
30t – 21t TorqueMaster 550
16t – 13t CrawlMaster 540
15t – 10t CrawlMaster 550
Puller Pro BL 540 Stubby or Standard
TrailMaster Pro BL 540
Revolver Snubnose 540 or Revolver 540 Sensorless
Stock gearing compatible with brushless and 550 size brushed motors.
540 size brushed motors may require gearing down, especially if increasing wheel and tire size.

Losi Baja Rey

General Trail use:
Puller Pro 540-L, 540 XL

Losi Night Crawler

General Trail use:
Puller Pro BL 540 Standard
TrailMaster Pro BL 540
Revolver 540 Sensorless

Losi Rock Rey

General Trail use:
Puller Pro BL 540 Standard, 540-L, 540 XL
TrailMaster Pro BL 540
Revolver 540 Sensorless

RC4WD Bully II

General Trail use:
40t – 27t TorqueMaster 540
16t – 13t CrawlMaster 540
Competition:
35t – 30t TorqueMaster 540
16t – 13t CrawlMaster 540
35t – 30t Puller 500 Flow
16t – 13t Puller 500 Crawl
~35:1 overall reduction from the motor output to the tires

RC4WD Gelande II

General Trail use:
35t – 27t TrailMaster Sport 540
27t – 21t TrailMaster Sport 550
35t – 27t TorqueMaster 540
30t – 21t TorqueMaster 550
16t – 13t CrawlMaster 540
15t – 10t CrawlMaster 550
Puller Pro BL 540 Stubby or Standard
TrailMaster Pro BL 540
Revolver Snubnose 540 or Revolver 540 Sensorless

Competition:
30t – 27t TorqueMaster 540
16t – 11t Crawlmaster 540

RC4WD Trail Finder 2

Motor Slot Speed Machine Slot Machines

General Trail use:
35t – 27t TrailMaster Sport 540*
27t – 21t TrailMaster Sport 550
35t – 27t TorqueMaster 540*
27t – 21t TorqueMaster 550
16t – 13t CrawlMaster 540*
15t – 10t CrawlMaster 550
Puller Pro BL 540 Stubby or Standard
TrailMaster Pro BL 540
Revolver Snubnose 540 or Revolver 540 Sensorless
Competition:
30t – 27t TorqueMaster 540*
16t – 11t Crawlmaster 540*
*540 size brushed motors will need to have motor temperatures closely monitored when using 2nd gear.
Stock gearing compatible with brushless and 550 size brushed motors.

Redcat Racing Gen8

General Trail use:
45t – 21t TrailMaster Sport 550 (12t is not suitable for crawling)
27t – 21t TorqueMaster 550
15t – 10t CrawlMaster 550
Puller Pro BL 540 Standard
TrailMaster Pro BL 540
Revolver 540 Sensorless

Traction Hobby Cragsman

General Trail use:
45t – 21t TrailMaster Sport 550
27t – 21t TorqueMaster 550

Traxxas Slash 4X4

General Trail use:
12t TrailMaster Sport 550

Traxxas Telluride 4X4

General Trail use:
12t TrailMaster Sport 550

Traxxas TRX-4

General Trail use:
27t – 21t TrailMaster Sport 550 (12t is not suitable for crawling)
27t – 21t TorqueMaster 550
15t – 8t CrawlMaster 550 (single speed transmission)
15t – 10t CrawlMaster 550 (two speed transmission)
Puller Pro BL 540 Standard
TrailMaster Pro BL 540
Revolver 540 Sensorless

Scatter Slots Slot Machines

Traxxas TRX-6

General Trail use:
27t – 21t TrailMaster Sport 550 (12t is not suitable for crawling)
27t – 21t TorqueMaster 550
15t – 10t CrawlMaster 550
Puller Pro BL 540 Standard
TrailMaster Pro BL 540
Revolver 540 Sensorless

Vanquish VS4-10

General Trail use:
35t – 27t TrailMaster Sport 540
27t – 21t TrailMaster Sport 550
35t – 27t TorqueMaster 540
27t – 21t TorqueMaster 550
16t – 13t CrawlMaster 540
15t – 10t CrawlMaster 550
Puller Pro BL 540 Stubby or Standard
TrailMaster Pro BL 540
Revolver Snubnose 540 or Revolver 540 Sensorless
Stock (15 tooth kit pinion/ 13 tooth RTR pinion / 56 tooth spur) gearing compatible with 35t TorqueMaster 540 and 16t CrawlMaster 540
Stock gearing compatible with brushless and brushed motors using stock tire sizes.
Brushed motors will require gearing down if increasing wheel and tire size.

Vanquish VS4-10 Pro

General Trail use:
35t – 27t TrailMaster Sport 540
35t – 27t TorqueMaster 540
16t – 13t CrawlMaster 540
Puller Pro BL 540 Stubby or Standard
TrailMaster Pro BL 540
Revolver Snubnose 540 or Revolver 540 Sensorless

Vaterra Ascender

Fox Slots Slot Machine Parts

General Trail use:
35t – 27t TrailMaster Sport 540
35t – 27t TorqueMaster 540
16t – 13t CrawlMaster 540
Puller Pro BL 540 Stubby or Standard
TrailMaster Pro BL 540
Revolver Snubnose 540 or Revolver 540 Sensorless