Torque multiplication versus slip
Torque multiplication versus slip
(OP)
Can anyone shed some light on the concept of torque multiplcation through an automatic transmission torque converter?
The best I can come up with is the idea that torque multiplication is proportional to the ratio of flexplate RPM and input shaft RPM much like it would be for a chain or a set of gears.
So for example engine at 5000 rpm and the input shaft is doing 2500 rpm in a perfect world the torque at the input shaft is twice that which the engine is creating.
Of course there is some significant losses at the extreme ends of the RPM ranges here otherwise torque would tend towards infinity when gearbox input shaft speed was zero.
When it comes to something viscous like a torque converter I just see the speed differential is a slippage which to me registers as an outright loss of energy.
Is there such a thing as a torque converter dyno that can show hard evidence of torque multiplcation?
The best I can come up with is the idea that torque multiplication is proportional to the ratio of flexplate RPM and input shaft RPM much like it would be for a chain or a set of gears.
So for example engine at 5000 rpm and the input shaft is doing 2500 rpm in a perfect world the torque at the input shaft is twice that which the engine is creating.
Of course there is some significant losses at the extreme ends of the RPM ranges here otherwise torque would tend towards infinity when gearbox input shaft speed was zero.
When it comes to something viscous like a torque converter I just see the speed differential is a slippage which to me registers as an outright loss of energy.
Is there such a thing as a torque converter dyno that can show hard evidence of torque multiplcation?





RE: Torque multiplication versus slip
"
Yes there is. OEMs have maps of torque converter performance. They are complex, but you have already identified the basics.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Torque multiplication versus slip
So for example engine at 5000 rpm and the input shaft is doing 2500 rpm in a perfect world the torque at the input shaft is twice that which the engine is creating."
Unlike direct mechanical transmission of chain or gear, torque converter transmits torque by fluid. A change of fluid moment generates torque multiplication. There is indeed energy loss in the fluid. For this reason, the torque multiplication ratio cannot be compared with gear sets. For instance, the maximum torque ration (in stall state when the input shaft of transmission stands still) is around 2.0.
RE: Torque multiplication versus slip
Blacksmith
RE: Torque multiplication versus slip
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Torque multiplication versus slip
If the pump and motor are made to displace different amounts of fluid per revolution, it is possible by design to get speed or torque multiplication.
RE: Torque multiplication versus slip
RE: Torque multiplication versus slip
RE: Torque multiplication versus slip
RE: Torque multiplication versus slip
RE: Torque multiplication versus slip
RE: Torque multiplication versus slip
Best regards,
Matthew Ian Loew
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.