Mecanum wheels, when properly set up on a drivetrain, allow for omni-directional movement. Each Mecanum Wheel Set (REV-45-1655) comes with a two right (REV-41-1656) and two left (REV-41-1657) mecanum wheels. This is determined by the direction of the leading edge of the rollers. If the rollers point left it is a left wheel and if they point right it is a right wheel.
Each side of the chassis needs one left and one right wheel. Mecanum Chassis also require four motors for operation.
To know if your Mecanum Wheels are properly configured look from the top down on the drivetrain. Following diagonal lines created from the angle of the rollers should form an "X" as shown above.
Running all four wheels in the same direction at the same speed will result in a forward/backward movement, as the longitudinal force vectors add up but the transverse vectors cancel each other out, as shown below.
When both wheels on one side of the drivetrain are moving in one direction while the other side is moving in the opposite direction results in stationary rotation of the drivetrain. The transverse vectors cancel out but the longitudinal vectors combine to generate rotation around the central vertical axis of the drivetrain, as shown below.
When the right mecanum wheels run in one direction while the left mecanum wheels run in the opposite direction allows for a strafing movement, as the transverse vectors add up but the longitudinal vectors cancel out.
Using the above concepts in tandem through varying motor power to each wheel type allows for the drivetrain to move in different, angled vectors.
Need help programming your mecanum drivetrain? Check out our Mecanum Drive Example Code Template and Configuration page!
This section outlines the steps required to build a mecanum drivetrain using parts from the Mecanum Drivetrain Kit (REV-45-1877). The Mecanum Drivetrain Kit uses Belts and Pulleys rather than the standard Chain and Sprocket. For instructions on how to build a mecanum drivetrain with Chain and Sprocket instead checkout the Channel Drivetrain - Mecanum Upgrade.
This design is a good starting point. However, modification maybe required to address the specific needs of the robot being designed.
The assembly of this drivetrain is broken into a few sections. This allows for a team of people to work on different tasks to complete the build quicker. Each section begins with what parts and the quantity of parts needed to complete the steps in that section. A list of required materials for all sections is listed below.
Full Assembly CAD File - STEP Format
This drivetrain can be built out of the following kits:
Part Number
Description
QTY.
Mecanum Drivetrain Kit
1
Part Number
Description
QTY.
FTC Starter Kit V3
1
75mm Mecanum Wheel Set
1
UltraPlanetary Gearbox Kit & HD Hex Motors
2
24 tooth GT2 3mm Pitch Pulley
4
120 tooth GT2 3mm Pitch Belt
2
5mm Hex Bearing Block
8
PART NUMBER
DESCRIPTION
QTY.
45MM X 15MM C CHANNEL - 408MM
4
45MM X 15MM C CHANNEL - 248MM
1
U CHANNEL ENDCAP
4
15MM EXTRUSION - 420MM
2
5MM X 75MM HEX SHAFT
2
5MM X 90MM HEX SHAFT
4
3MM SPACER
16
15MM SPACER
4
THROUGH BORE BEARING - SHORT
6
24 TOOTH GT2 3MM PITCH PULLEY
4
120 TOOTH GT2 3MM PITCH BELT
2
5MM HEX BEARING BLOCK
8
SHAFT COLLAR
10
ULTRAPLANETARY GEARBOX KIT & HD HEX MOTOR
4
ULTRAPLANETARY OUTSIDE MOUNTING BRACKET
4
15MM PLASTIC 90 DEGREE BRACKET
12
75MM MECANUM WHEEL SET
1
M3 X 8MM HEX CAP SCREWS - 100 PACK
2
M3 NYLOC NUTS - 100 PACK
1
This build also requires a number of tools.
Part Number
Description
2mm Allen Wrench
1.5mm Allen Wrench
5.5mm Combination Wrench
5.5mm Nut Driver
2.5mm Allen Wrench*
*The 2.5mm Allen Wrench is needed for final assembly of the UltraPlanetary Gearbox and not included in the Mecanum Drivetrain Kit
*
PART NUMBER
DESCRIPTION
QTY.
24 TOOTH GT2 3MM PITCH PULLEY
4
Take the two ends of the 24 Tooth GT2 3mm Pitch Pulley and fit them together.
Note: The pulley ends should be flush with each other.
Lock the pulley ends together using three of the screws that came with the pulleys.
PULLEY ASSEMBLY COMPELTE
Repeat this step until you have four completed Pulley Assemblies.
PART NUMBER
DESCRIPTION
QTY.
45MM X 15MM C CHANNEL - 408MM
2
U CHANNEL ENDCAP
2
5MM HEX BEARING BLOCK
4
M3 X 8MM HEX CAP SCREWS
36
M3 NYLOC NUTS
8
5MM X 75MM HEX SHAFT
1
5MM X 90MM HEX SHAFT
2
3MM SPACER
6
SHAFT COLLAR
3
THROUGH BORE BEARING - SHORT
3
120 TOOTH GT2 3MM PITCH BELT
1
ASSEMBILIES
ULTRAPLANETARY ASSEMBLY
2
PULLEY ASSEMBLY
2
Attach an UltraPlanetary Assembly to a 45mm x 15mm C Channel - 408mm. Place M3 Screws and M3 Lock Nuts in the correct locations. Tighten until nuts are snug.
Note: The Output Cartridge of the UltraPlanetary Gearbox lines up with the fourth large (9mm) hole from the end of the C Channel.
Attach an UltraPlanetary Assembly to a 45mm x 15mm C Channel - 408mm. Place M3 Screws and M3 Lock Nuts in the correct locations. Tighten until nuts are snug.
Note: The Output Cartridge of the UltraPlanetary Gearbox lines up with the thirteenth large (9mm) hole from the end of the Channel.
Attach a Hex Bearing Block to a 45mm x 15mm C Channel - 408mm using M3 x 8mm Screws. Tighten until screws are snug.
Note: The Hex Bearing Block lines up with the Forth large (9mm) hole from the end of the Channel.
Attach a U Channel End Cap to the Motor end of the C Channel. Add three Hex Cap Screws to hold it in place. Tighten the Hex Cap Screws.
Attach a U Channel End Cap to the other end of the C Channel. Add three Hex Cap Screws to hold it in place. Tighten the Hex Cap Screws.
In the following section 5mm Hex Shafts will be placed on the Drive Rail. This is be doing to get correct spacing on the Shafts. However the Shafts will not be be secure until the end of the assembly and may come loose during the building process.
Add a 75mm Hex Shaft to the second motor on the Drive Rail.
Add a 90mm Hex Shafts to the first motor and the Hex Bearing Block
Add three 3mm Spacers the 75mm Hex Shaft that is on the second motor.
Add two 24 Tooth GT2 3mm Pitch Pulleys to the shaft on the second motor and the Hex Bearing Block Shaft.
Add Shaft Collars to all three Hex Shafts. Do not tighten any of the shaft collars.
Note: At this point nothing has been added to put space between the first motor and the Shaft Collar. This Shaft Collar can be adjusted after the second C Channel is placed. In general it is better to situate the shaft collar away from the motor to make adjustments easier.
Add Through Bore Bearings - Short to all three Hex Shafts.
Note: the smaller portion of the bearing faces away from the Shaft Collar.
Add 3mm Spacers to all three Hex Shafts.
Slide the 120 Tooth GT2 3mm Pitch Belt onto the Pulleys.
Note: The easiest way to add the Belt to the assembly is to remove either the second motor shaft or the Hex Bearing Block Shaft. Hook the Belt over both Pulleys so that the teeth of the Belt are meshed with the Pulley. Then replace the displace shaft to its original position.
Add Hex Bearing Blocks to all three shafts.
Note: The Hex Bearing Blocks will rotate on the shafts. This is fine but for the next step they need to be oriented as shown in the image.
Add a Channel – 408mm to close out the Drive Rail.
Note: Make sure the Bearing Blocks are square and the Channel End Cap holes line up.
Take eighteen 8mm Hex Cap Screws and secure the 45mm X 15mm C Channel – 408mm to the rest of the assembly. Screw into the End Caps and the Bearing Blocks to keep everything in place.
DRIVE RAIL ASSEMBLY COMPLETE
Adjust Shaft Collars and tighten set screws.
Repeat these steps until you have two Drive Rail Assemblies.
The FTC Starter Kit comes with two of the UltraPlanetary Gearbox Kits with HD Hex Motors. This is an entry point into using the REV UltraPlanetary System. There are three UltraPlanetary Cartridges supporting seven different final gear reductions ranging from nominally 3:1 to 60:1. This allows for the right amount of torque for the application at hand. The motor provided already has the pinion gear pressed onto it making assembly of gearboxes easier.
When getting started with this drivetrain, it is recommended to use a nominal 20:1 Gear Ratio. This uses the UltraPlanetary 5:1 Cartridge and the UltraPlanetary 4:1 Cartridge. For more information on all gear ratio options, load ratings, and more, see the UltraPlanetary Gearbox User’s Manual on revrobotics.com.
PART NUMBER
DESCRIPTION
QTY.
M3 X 8MM HEX CAP SCREWS
6
ULTRAPLANETARY OUTSIDE MOUNTING BRACKET
1
PARTS WITHIN THE ULTRAPLANETARY GEARBOX KIT
HD HEX MOTOR
1
ULTRAPLANETARY PINION GEAR (ON HD HEX MOTOR)
1
ULTRAPLANETARY MOUNTING PLATE
1
ULTRAPLANETARY CARTRIDGE 4:1
1
ULTRAPLANETARY CARTRIDGE 5:1
1
ULTRAPLANETARY OUTPUT STAGE
1
M3 X 30MM CAP HEAD SCREW
6
M3 X 8MM BUTTON HEAD SCREW
2
Attach the UltraPlanetary Mounting Plate to the HD Hex Motor using two 8mm Button Head Screws.
Note: Use the 2mm Allen Key to tighten these screws.
Seat the UltraPlanetary 5:1 Cartridge onto the input pinon.
Note: Placing a finger on the output of the 5:1 Cartridge and turning it helps for placement.
Seat the UltraPlanetary 4:1 Cartridge onto the UltraPlanetary 5:1 Cartridge.
Note: Placing a finger on the output of the 4:1 Cartridge and turning it helps for placement.
Seat the UltraPlanetary Output Stage onto the UltraPlanetary 4:1 Cartridge.
Note: Placing a finger on the output of the Output Cartridge and turning it helps for placement.
Insert six of the 30mm Cap Head Screws into the holes in the outer ring off the Output Cartridge.
Tighten these screws down until they are snug not tight using a 2.5mm allen wrench.
Note: The 30mm length is the 2nd longest screw provided with the UltraPlanetary Gearbox Kit.
Remove the set screw from the UltraPlanetary Output before attaching the Outside Mounting Plate.
Align the UltraPlanetary Outside Mounting Bracket with the mounting holes on the Output Cartridge.
Insert six 8mm Hex Cap Screws into the mounting holes.
Tighten the screws until they are snug.
ULTRAPLANETARY ASSEMBLY COMPLETE
Repeat the above steps until there are four completed UltraPlanetary Assemblies. Set aside for later.
OR
PART NUMBER
DESCRIPTION
QTY.
15MM PLASTIC 90 DEGREE BRACKET
12
M3 X 8MM HEX CAP SCREWS
60
M3 NYLOC NUTS
60
Take a bracket and finger start one Hex Cap Screw and Nyloc Nut per hole.
Note: The side of the bracket with “ribs” must have the Hex Cap Screw head.
PRE-LOADED BRACKET COMPELTE
Repeat this step until you have twelve Pre-Loaded Brackets.
75MM MECANUM WHEEL
4
UNIVERSAL HEX ADAPTER
4
M3 X 8MM HEX CAP SCREWS
16
The Universal Hex Adapter V2 (REV-41-1833) can be substituted for the Universal Hex Adapter. 75mm Mecanum Wheel sets purchased after 1/10/2020 will include the Universal Hex Adapter V2.
Add the Universal Hex Adapter to the Mecanum Wheel using four 8mm x M3 Screws
MECANUM WHEEL ASSEMBLY COMPLETE Repeat the above step until you have four Mecanum Wheel Assemblies.
PART NUMBER
DESCRIPTION
QTY.
45MM X 15MM C CHANNEL - 248MM
1
15MM EXTRUSION - 420MM
2
15MM SPACER
8
3MM SPACER
4
SHAFT COLLAR
4
ASSEMBLIES
DRIVE RAIL ASSEMBLY
2
PRE-LOADED BRACKET
12
MECANUM WHEEL ASSEMBLY
4
Slide the four Pre-Loaded brackets onto the Drive Rail Assembly as shown.
Align the Pre-Loaded Brackets where 6 Hex Cap Screws and Nylock Nuts are exposed.
Add two Pre-Loaded Brackets to the Motor side C Channel.
Use landmarks like the UltraPlanetary Output Bracket of the 9mm Bearing Seat on the Channel to align both 90 Degree Brackets to the same position on the Channel.
Tighten the Nyloc Nuts until they are snug
Slide the 45mm X 15m C Channel - 248MM onto the Preloaded Brackets as shown.
Tighten the Nyloc Nuts until they are snug.
Repeat sliding four Pre-Loaded brackets onto the other Drive Rail Assembly as shown.
Repeat aligning the Pre-Loaded Brackets where 6 Hex Cap Screws and Nylock Nuts are exposed.
Repeat adding Pre-Loaded Brackets to the Motor side C Channel.
Use the same landmark from a few steps ago to align both 90 Degree Brackets to the same position on the Channel as the 90 Degree Brackets on the other Drive Rail.
Tighten the Nyloc Nuts until they are snug
Slide the second Drive Rail on.
Once in place, tighten the Nyloc Nuts until they are snug.
Slide two pieces of 15mm Extrusion – 420mm into the Pre-Loaded Brackets until they are through both sets brackets. One 15mm Extrusion is for the top and the other for the bottom.
Align the 15mm Extrusion – 420mm so approximately the same amount of Extrusion is left on the end of each Bracket.
Tighten the Nyloc Nuts until they are snug.
Add a 15mm Spacer followed by a 3mm Spacer to the 90mm Hex Shafts that act as the Drive Shafts.
Take the Mecanum wheels and place on the shafts as shown.
Note: See the steps below to see how to place the left and right Mecanum Wheels.
Each Mecanum Wheel Set comes with two right (REV-41-1656) and two left (REV-41-1657) mecanum wheels. This is determined by the direction of the leading edge of the rollers. If the rollers point left it is a left wheel and if they point right it is a right wheel.
Each side of the chassis needs one left and one right wheel. Place the wheels as shown.
Add one shaft collar to the end of each drive shaft.
Tighten down the shaft collars on each wheel to secure them in place.
DRIVETRAIN COMPLETE
See theSection for more information.
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