From VEX Wiki
This kit provides several options for advanced motion. The kit consists of 4 main sub-components: bevel-gears, rack-and-pinions, worm-gears, and a differential. These parts allow advanced mechanical Vex designers to create new ingenious mechanisms.
Rack & Pinion
The first set of components in this kit is the Rack & Pinion setup. The rack gears included in this kit can be used to create linear motion. These rack gears can be attached to any Vex metal component (using the included 6-32 screws), and driven by any Vex spur gear. As the pinion gear rotates, the rack gear will slide linearly. This allows users to create linear motion. For every rotation of the shaft, the rack gear will advance a number of teeth equal to that of the pinion. So for a 12 tooth pinion gear, 1 rotation will advance the rack gear by 12 teeth. The rack gear consists of 19 teeth, and is 2.5” long. This means for every 19 teeth it advances, it will move 2.5” linearly.
Bevel Gears
Another component found in the advanced gear kit is a bevel gear. Bevel gears can be used to transmit motion “around corners” in 90˚ angles. This is useful for many applications. All the bevel gears included in this kit have 24-teeth. This results in a 1-to-1 reduction (the output shaft spins with the same speed & torque of the input shaft.)
Differential
The bevel gears can also be used in conjunction with the differential frame to create a differential. Simply install (3x) of the bevel gears into the differential frame as shown. Two of the bevel gears will snap into sockets in the plastic differential housing, the third bevel gear must be held in place by a Vex shaft. Note: you may need to bend the frame slightly during installation to get everything snapped into place. Once the gears are installed, you can then integrate this differential assembly into your robot to allow for “car-style” rear drive. When a car turns one rear wheel moves in a larger arc than the other wheel. The wheel on the outside of the turn needs to move further (and spin faster) than the wheel on the inside of the turn. The differential allows both of these wheels to be driven from a single power-source, and still allows them to spin at different rates in a turn. Though differentials have many uses, this is the most common.
Worm Gear
The final component of the advanced gear kit is the worm-gear. Worm gears are useful for several reasons.
- Like the bevel gears, they offset motion 90 degrees.
- Worm-gear drives also resist “backdriving”, if you try to use a wormwheel to drive a worm-gear, it won’t work! The driving force must be applied to the worm gear.
- This resistance to back-driving can be very useful in any number of robot applications.
- Worm gears will also provide a high amount of reduction, in a relatively compact package.
The worm-wheel included in the Vex advanced gear kit has 24-teeth. For every full revolution of the worm-gear, the worm wheel will advance 1-tooth (1/24th of a revolution). This means, the worm-gear must spin 24 times before the wormwheel will complete a single revolution.
Specifications
|
Compatibility
- All VEX Square Shafts 0.125" (3.2mm).
- Rack Gears and Differential Frame mate with all VEX Spur Gears.
- Worm Gears only mate with the Worm wheel.
- 24-tooth bevel gear only mate with themselves.
Material Type
-
|
Differential Frame
- Requires (3) 24-tooth bevel gear to make a functional differential.
Rack Gear
- These can be combined continuously to create a rack of 20" (508mm)
Size
- Worm Gear:0.75" (19.1mm) long
- Rack Gear:2.50" (63.5mm) long
|
