- First Slot Machine
- Motor Slot Speed Machine Slot Machines
- Scatter Slots Slot Machines
- Fox Slots Slot Machine Parts
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.
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 Type | 3 slot straight armature | 3 slot skewed armature | 5 slot straight armature | 5 slot skewed armature | Brushless |
Fastest | 4500kv | ||||
4100kv | |||||
3800kv | |||||
3500kv | |||||
3300kv | |||||
TrailMaster Sport 550 12t | 3100kv | ||||
CrawlMaster Pro 540 11t | Puller 400 Crawl 13t Puller 500 Crawl 11t | 2700kv | |||
CrawlMaster Sport 550 8t | 2300kv | ||||
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 11t | 1850kv | |
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 16t | 1500kv | |
CrawlMaster Sport 550 13t | 1450kv | ||||
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 20t | 1250kv | ||
TorqueMaster Magnum 540 38t | 1200kv | ||||
TorqueMaster 540 45t | 1100kv | ||||
Slowest | TorqueMaster 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
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
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