Plummer Industries

Drive Rail Information and Instructions

Drive Rails are designed to be a lightweight easy to use solution for FRC drivetrain. They are made from 3" by 1.5" .125" wall 6061-T6 aluminum tubing. 

The Drive Rail System allows teams in FRC to get the exact drive base they want in an inexpensive and compact platform while still being one of the lightest weight options on the market. 

All Drive Rails are 1 or more inches longer than the leading edge of the wheel to allow teams to mount a piece of 1 inch extrusion there to mount bumpers and complete their frame perimeter without having to make complicated brackets or adapters.

Our Drive Rails are designed to give you flexible ways to mount them to your robot. With all holes on 1 inch center to center teams can easily integrate 1 inch aluminum extrusion like 80-20 or rev extrusion as well as use our gussets or other commonly available gussets to brace to them. All mounting holes are sized to clearance for a number 10 and can be tapped for a 1/4 -20 or drilled out for whatever need you may have.

All Drive Rail Products are shipped with output shafts that are made for a 1.5 inch wide wheel assembly. If custom lengths are required we recommend using West Coast Products or Vex Pro 1/2 hex shaft (217-3309) and cutting the shafts 1/16 shorter than needed to allow the wheel bolts to torque properly.


Drive Rail Assembly Instructions


DR-2 -

When assembling your Drive Rail 2 you should need the following tools-

  •  5/32"  Hex key or T- handle
  1. Start with all the 1/2 inch hex shafts laid out on the table. Add an included 1/4-20 x 1/2" button head screw and washer to one end of each shaft and just finger tighten.
  2. Take both 1.5" hex shafts and slide on a bearing (flange side toward screw) followed by the smallest 1/2" hex bore gear in your kit.
  3. Take both 3" hex shafts and slide on a bearing (flange side toward screw) followed by the 1/2" spacer.
  4. Lay drive rail on table as at would be oriented in the robot and roll the 52 Tooth Gear down the inside of the rail until it lines up with the bearing hole closest to the motor input.
  5. Take your 1.5" Hex shaft assembly and from the output side slide it into the 52 tooth gear. 
  6. Add bearing and hardware to far side of shaft.
  7. Roll the Output gear down the inside of the rail until it lines up with the output bearing locations.
  8. Insert the output shaft assembly to through the output gear from the input side.
  9. Add bearing and hardware to far side of shaft.
  10. Repeat for both ends of rail.
  11. Install cim input gear onto motor.
  12. Place cim spacer onto cim and align holes
  13. Insert motor assembly into input of Drive Rail and install both 5/8 10-32 button head screws.
  14. Repeat for second motor.
  15. Torque all hardware to specifications.

DR-3 and 4-

When assembling your Drive Rail 2 you should need the following tools-

  •  5/32"  Hex key or T- handle
  1. Decide where you want your input from your gearbox to be.
  2. Take output pulley and wrap belt around it and insert into the end of the drive rail.
  3. Depending on where you want your input to be you need to put the input pulley in the right order.
  4. Slide all pulleys wrapped in belts into end of tube in correct order making sure that the belts are on alternating sides of the pulleys.
  5. Take all output shafts and install a 1/4 - 20 button head screw and washer into one end.
  6. Place bearings on each output shaft with the flange closer to the screw.
  7. Place 1/16 spacers onto each shaft
  8. Insert shaft assemblies into pulleys through bearing holes and add another 1/16 spacer and bearing to other side of shaft.
  9. Pull belts tight and push both side bearings into housing working your way down rail until all belts are tight.
  10. Install gearbox of your choice.
  11. Install wheels of your choice.

Drive Rail Selector

The best way to figure out what drive rail is best for your application we recommend asking yourself the following questions.

- Do your need to drive wheels that are on the same side individually? ( ie. Mechanum )

     -If yes, you should be looking at our DR-2 line

- How many wheels do you want per side of your robot?

- How long do you want your robot to be? (direction of drive)

    -We currently offer 24", 30", and 36" lengths

    - With our Brackets it is easy to add one or two inches to any Drive Rail

- How much ground clearance do you need? ( Think about how high you want to mount your mechanisms to as well) 

    - The DR-2 ground clearances are 1/2" with a 4" wheel and 1.5" with a 6" wheel

    - The DR-3 and DR-4 maximum* ground clearances are .5" with 2.5" wheels, .75" with 3" wheels, 1" with 4" wheels, 1.5" with 6" wheels, 2.5" with 8" wheels. 

*Maximum ground clearance is from the rail next to the center wheel to the ground. As there is a 1/8" drop on the center wheel there will be at least 1/8" less clearance on both ends.

- How fast do you want your robot to go?

      - For all our drive rails we offer 3 different gearing options

DR-2 Speeds
Gear Ratios 12.51 to 1 10.83 to 1 8.3 to 1
4" Wheels~7 Fps~8 Fps~10.5 Fps
6" Wheels~10.5 Fps~12 Fps~15.5 Fps


DR-3 and DR-4 Speeds

Gear Ratios for SS-3-775

40.47 to 129.62 to 125.83 to 1
2.5" , 3" , and 4" Wheels~8.5 Fps~11.5 Fps~13.5 Fps
6" Wheels~10 Fps~14 Fps~16 Fps
8" Wheels~11.5 Fps~15.5 Fps~18 Fps
Gear Ratios for SS-2-Cim17.8 to 115.5 to 112.05 to 1
2.5" , 3" , and 4" Wheels~6 Fps~7  Fps~9 Fps
6" Wheels~7.25 Fps~8.25 Fps~10.75 Fps
8" Wheels~8.75 Fps~10 Fps~ 13 Fps


Now, with all those questions answered you should be able to put together a part number for a drive rail.

DR- (Number of wheels per side) - (Length of rail) - (Wheel size) 

   - For DR-2 models the part number also include a gear ratio number as the last part number


DRive Rail Videos

DR-3 and 4 Assembly

DR-2 Assembly