Dagu Wild Thumper 4WD All-Terrain Chassis, Black, 75:1

This rugged, 4-wheel-drive chassis from Dagu Electronics is a smaller version of the Wild Thumper 6WD chassis. It is designed to excel at traversing rough terrain, making it a great platform for any robot that needs to perform tasks in a complex outdoor environment. It features four powerful DC motors with brass brushes and 34:1 or 75:1 steel gearboxes that drive large (120mm diameter) spiked tires, and a unique “super-twist” suspension system acts to keep each wheel in contact with the ground for maximum traction, even when driving over uneven or bumpy surfaces. The suspension can be adjusted to suit different loads and conditions. The chassis is made from a 2mm-thick corrosion-resistant anodized aluminum plate, all of the nuts, bolts, and screws are stainless steel, and the brass fittings and suspension springs are nickel-plated.

When powered at 7.2 V, the version of the chassis with 34:1 gearboxes can reach a top speed of approximately 7 km/h (4.5 mph), and each motor has a stall torque of roughly 5 kg-cm (70 oz-in). At the same voltage, the version of the chassis with 75:1 gearboxes can reach a top speed of approximately 3 km/h (2 mph), and each motor has a stall torque of roughly 11 kg-cm (150 oz-in).

Using the Chassis:

The chassis’ aluminum plate has 4mm holes spaced every 10mm, providing plenty of options when it comes to mounting your control electronics, sensors, and additional hardware. A compartment in the chassis has been designed to hold 7.2 V sub-C battery packs (not included) that are commonly used in RC cars. Two such battery packs can fit in the compartment. The interior of the chassis also features convenient screw terminals for connecting your battery and motor driver leads. The motor leads are pre-connected to these screw terminals.

This is a differential-drive chassis, meaning that turning is accomplished by driving the motors on the two sides of the platform at different speeds. The two motors on each side of the robot are wired in parallel, so only two channels of motor control are required to get this chassis moving. The motors are intended for a maximum nominal operating voltage of 7.2 V (2 V minimum), and each has a stall current of 6.6 A and a no-load current of 420 mA at 7.2 V. Since the motors will briefly draw the full stall current when abruptly starting from rest (and nearly twice the stall current when abruptly going from full speed in one direction to full speed in the other), we recommend a motor driver capable of supplying the 14 A combined per-channel stall current of these motors at 7.2 V. We offer several motor controllers and drivers that meet these power requirements and make it easy to get this chassis moving:

• The High-Power Simple Motor Controller G2 18v15 offers a variety of control interfaces: USB, TTL serial, I²C, analog voltage (for control from a potentiometer or analog joystick), and RC hobby servo pulses. These controllers are highly configurable and the USB interface makes them easy to set up and use. Since the SMC is a single-channel controller, you would need to use two with the Wild Thumper, one for each side of the chassis.
• The RoboClaw 2×15A Motor Controller is another motor controller option with many control interfaces including: USB, TTL serial, analog voltage (for control from a potentiometer or analog joystick), and RC hobby servo pulses. These controllers are dual channel, so only one is required for controlling the chassis.
• The Dual G2 High-Power Motor Driver 18v18 Shield for Arduino or Dual VNH5019 Motor Driver Shield for Arduino are easy to control with an Arduino, and either can also be used with other microcontroller boards as general-purpose dual motor drivers. Since they are just motor drivers, they lack many of the advanced features of the Simple Motor Controller (like built-in acceleration limiting or high-level interfaces such as USB and RC), but such features might not be necessary if your goal is to make a basic autonomous robot. Since these are dual channel drivers, only one shield is needed to control the Wild Thumper.

Specifications: 

• Size: 280 × 300 × 130 mm (11" × 12" × 5")
• Weight: 1.9 kg (4.1 lb)
• Ground clearance: 60 mm (2.5") when lightly loaded
• Recommended motor voltage: 2 V to 7.5 V
• Stall current at 7.2 V: 6.6 A per motor
• No-load current at 7.2 V: 420 mA per motor
• No-load output shaft speed at 7.2 V:
  • 350 RPM for the version with 34:1 gearboxes
  • 160 RPM for the version with 75:1 gearboxes
• Stall torque at 7.2 V:
  • 5 kg-cm (70 oz-in) per motor for the version with 34:1 gearboxes
  • 11 kg-cm (160 oz-in) per motor for the version with 75:1 gearboxes

Chassis Options:

This chassis is available in two different colors (silver and black) and with two different gear ratios (34:1 and 75:1):

• Silver 4WD with chrome-colored hubs and 34:1 gearmotors
• Silver 4WD with chrome-colored hubs and 75:1 gearmotors
• Black 4WD with metallic-red hubs and 34:1 gearmotors
• Black 4WD with metallic-red hubs and 75:1 gearmotors

If you are looking for a bigger robot that is better at scaling inclines and traversing larger obstacles, please consider one of the Wild Thumper 6WD models:

• Silver 6WD with chrome-colored hubs and 34:1 gearmotors
• Silver 6WD with chrome-colored hubs and 75:1 gearmotors
• Black 6WD with metallic-red hubs and 34:1 gearmotors
• Black 6WD with metallic-red hubs and 75:1 gearmotors

The higher gear ratio version has a lower top speed but can produce greater torque. Note that while the Wild Thumper 4WD chassis includes four wheels, the wheels can be purchased in pairs for use as replacement Wild Thumper parts or as wheels for custom chassis. The wheels are available with metallic-red hubs and chrome-colored hubs. We also offer the Wild Thumper gearmotors individually in a wide range of gear ratios (versions with integrated quadrature encoders are also available, though these will not work with the Wild Thumper chassis).