These planetary, spur and worm dc gear motors with various gear ratio are widely used as door opener motor, gate operator motor, electric vehicle motor, truck lift motor, stair lift motor, medical bed motor, salt spreader motor etc 28MM PLANETARY GEARBOX, 12V 24V BRUSHED DC GEAR MOTOR. Gear ratio options: 3.7, 5.2, 14, 19, 27, 51, 71, 100