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by SigmundA
944 days ago
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I posted below but you cannot fully simulate a locker with independent motors. The quad motor Rivian is actually inferior to the dual motor for rock crawling due to this. The quad motor Rivian produces 908 lbs/ft of torque which means each motor produces 908/4 = 227 lbs/ft. It has a single speed gear ratio of 12.6:1 meaning each wheel can get a maximum of 227 * 12.6 = 2860.2 lbs/ft wheel torque. The dual motor Rivian produces 829 lbs/ft of torque which means each motor produces 829/2 = 414.5 lbs/ft. It has has a single speed gear ratio of 13.7:1 (11:1 front) in the rear meaning each rear wheel can get a maximum of 414.5 * 13.7 = 5678.65 lbs/ft wheel torque (4559.5 front) with brake locking diff. Contrast this with a Jeep Wrangler which can put out 20,000 to 30,000 lbs/ft of torque to any single wheel through its torque converter, transmission, transfer case and axle gearing which can be over 100:1 in gear ratio and single ICE. There are videos of Rivian's stalling rock crawling that are no issue for an old Jeep with weak engine due to lack of torque to the wheels. EV's will need lockers and probably at least two speed transmission to compete here, or they will need way oversized quad motors to make enough low speed torque without the gearing and lockers. |
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