75:1 Metal Gearmotor 25Dx66L mm HP 12V with 48 CPR Encoder (No End Cap)

Pololu item #: 3218
Brand: Pololu
Status: Obsolete 

This product has been discontinued.

This gearmotor has been replaced by a functionally identical version with a removable protective end cap over the encoder

This gearmotor consists of a high-power, 12 V brushed DC motor combined with a 74.83:1 metal spur gearbox, and it has an integrated 48 CPR quadrature encoder on the motor shaft, which provides 3591.84 counts per revolution of the gearbox’s output shaft. The gearmotor is cylindrical, with a diameter just under 25 mm, and the D-shaped output shaft is 4 mm in diameter and extends 12.5 mm from the face plate of the gearbox.

Key specifications:

voltage no-load performance stall extrapolation
12 V 130 RPM, 300 mA 17 kg⋅cm (240 oz⋅in), 5.6 A

You can use the following selection boxes to choose from all of our 25D metal gearmotor versions:

Alternatives available with variations in these parameter(s): gear ratio motor type encoders? Select variant…

 Description Specs (14) Pictures (14) Resources (4) FAQs (2) On the blog (0) 
I need additional information about this motor; do you have a datasheet?

No; the information we have available for this motor can be found on its product page. However, you can approximate various additional motor parameters from the information found in the “Specs” tab.

The electrical resistance of the motor can be approximated by dividing the rated voltage by the stall current (at the rated voltage). The electromotive force constant (Ke) can be approximated by dividing the rated voltage by the free-run speed (at the rated voltage). To approximate the motor torque constant (Kt), you can divide the stall torque by the stall current.

For pretty much any DC motor, the current, speed, power, and efficiency curves as a function of torque will look like those in the graph below (assuming motor voltage and temperature are constant):

The current and speed curves are approximately linear, and the product pages for our motors provide the approximate end points for these lines: (0 torque, no-load current) and (stall torque, stall current) for the red line, and (0 torque, no-load speed) and (stall torque, 0 speed) for the blue line.

The orange output power curve is the product of the speed and the torque, which results in an inverted parabola with its peak at 50% of the stall torque.

The green efficiency curve is the output power divided by the input power, where the input power is current times voltage. The voltage is constant, so you can divide the output power curve by the current line to get the general shape of the efficiency curve, which in turn lets you identify the torque, speed, and current that correspond to max efficiency.

There are many programs out there that you can use to generate these curves. For example, if you have access to MATLAB, you can use this customer-created MATLAB script to generate these motor plots for you from the specifications we provide for each gearmotor.

Note: A good general rule of thumb is to keep the continuous load on a DC motor from exceeding approximately 20% to 30% of the stall torque. Stalling gearmotors can greatly decrease their lifetimes, occasionally resulting in immediate damage to the gearbox or thermal damage to the motor windings or brushes. Do not expect to be able to safely operate a brushed DC gearmotor all the way to stall. The safe operating range will depend on the specifics of the gearmotor itself.

What material is the gearbox output shaft made of, and can I get the shaft customized?
The shaft is composed of hardened stainless steel. Some customization is generally possible (e.g., different length or no D-shaft) for sufficiently high-volume orders. If this is something you are interested in, please email us.

Related Products

Pololu 25D mm Metal Gearmotor Bracket Pair
Pololu Universal Aluminum Mounting Hub for 4mm Shaft, #4-40 Holes (2-Pack)
Pololu Universal Aluminum Mounting Hub for 4mm Shaft, M3 Holes (2-Pack)
Pololu Aluminum Scooter Wheel Adapter for 4mm Shaft
12mm Hex Wheel Adapter for 4mm Shaft (2-Pack)
Dagu Wild Thumper Wheel 120x60mm Pair with 4mm Shaft Adapters - Metallic Red
Dagu Wild Thumper Wheel 120x60mm Pair with 4mm Shaft Adapters - Chrome
Pololu Wheel 60×8mm Pair - Black
Pololu Wheel 90×10mm Pair - White
TB9051FTG Single Brushed DC Motor Driver Carrier
VNH5019 Motor Driver Carrier
Pololu G2 High-Power Motor Driver 24v13
Dual TB9051FTG Motor Driver Shield for Arduino
Pololu Dual VNH5019 Motor Driver Shield for Arduino
Pololu Dual G2 High-Power Motor Driver 24v14 Shield for Arduino
High-Power Simple Motor Controller G2 24v12 (Connectors Soldered)
Jrk G2 24v13 USB Motor Controller with Feedback
Jrk G2 21v3 USB Motor Controller with Feedback
Pololu Qik 2s15v9 Dual Serial Motor Controller

Related Categories

Pololu Wheels and Tracks
RoboClaw Motor Controllers
Brushed DC Motor Controllers
Brushed DC Motor Drivers
Robot Controllers
Current Sensors
37D Metal Gearmotors
20D Metal Gearmotors
Micro Metal Gearmotors
Wild Thumper All-Terrain Chassis
Log In
Pololu Robotics & Electronics
Shopping cart
(702) 262-6648
Same-day shipping, worldwide
Menu
Shop Blog Forum Support
My account Comments or questions? About Pololu Contact Ordering information Distributors