View Full Version : RX8 Rack-and-pinion steering


salituro64
02-25-2005, 08:57 AM
Does anyone know exactly what this means...

Rack-and-pinion steering with electric variable assist

Rotario
02-25-2005, 09:04 AM
Does anyone know exactly what this means...

Rack-and-pinion steering with electric variable assist
Yeah: the power assist for the steering is provided by an electric motor, rather than the (more usual) hydraulic pump powered off a belt by the engine.

salituro64
02-25-2005, 10:11 AM
Thanks, after posting I found it on the Mazda web site...

Electronic Power-Steering Pump - The Mazda RX-8's electric power-steering pump delivers precisely the right amount of assist to match driving conditions. One additional benefit of an electric power-steering pump is improved fuel economy, as electrically driven steering, as opposed to the typical belt-driven system, does not drain power from the engine.

Frank Patrick
02-25-2005, 11:19 AM
35 mpg

Mr M
02-28-2005, 01:14 PM
Thanks, after posting I found it on the Mazda web site...

Electronic Power-Steering Pump - The Mazda RX-8's electric power-steering pump delivers precisely the right amount of assist to match driving conditions. One additional benefit of an electric power-steering pump is improved fuel economy, as electrically driven steering, as opposed to the typical belt-driven system, does not drain power from the engine.

Does it really say "pump" on the web site? That would be a laugh, since there is no pump, just an electric motor that directly drives the steering rack.

salituro64
02-28-2005, 03:49 PM
MrM--->That was copied from the web site. I didn't even realize the wrong use of words. Good Catch.

Mr M
03-01-2005, 02:47 PM
Funny....
Without pics it is hard to explain, but the steering rack is encapsuled by the permanent magnets of an electric motor, with the armature spinning around the rack inside these permanent magnets. Connected to the armature is a ball-nut, which meshes with the rack teeth. When the armature rotates, so does the ball-nut, thus pulling the rack. Reverse the rotation of the motor and you have assist in the opposite direction.
There is a torque sensor attached to the steering shaft (at the rack) which detects how much torque is being applied to the shaft, and of course the vehicle speed is being picked up via the CAN communication system. When you have more torque you have more assist (higher current to the motor), when you have higher vehicle speed the assist is reduced.
Just in case you were interested - I hope I didn't lose you...

Cheers.

salituro64
03-02-2005, 06:57 AM
Funny....
Without pics it is hard to explain, but the steering rack is encapsuled by the permanent magnets of an electric motor, with the armature spinning around the rack inside these permanent magnets. Connected to the armature is a ball-nut, which meshes with the rack teeth. When the armature rotates, so does the ball-nut, thus pulling the rack. Reverse the rotation of the motor and you have assist in the opposite direction.
There is a torque sensor attached to the steering shaft (at the rack) which detects how much torque is being applied to the shaft, and of course the vehicle speed is being picked up via the CAN communication system. When you have more torque you have more assist (higher current to the motor), when you have higher vehicle speed the assist is reduced.
Just in case you were interested - I hope I didn't lose you...

Cheers.

Thanks

expo1
03-02-2005, 07:15 AM
This pic might help. It's a RHD set-up but if you follow the linkage from the steering wheel it should make sense

http://www.sendersnj.com/rx8/mike/rx8club/power_train_close.jpg