If you roll a standard shift car with the key on and pop the clutch with it in gear it will start. Why does that happen and why can't you do that in a car with an automatic transmision?
2007-01-19 00:48:35 · 8 answers · asked by canela 5 in Cars & Transportation ➔ Other - Cars & Transportation
A standard shift car uses a solid connection (the clutch and transmission gears) between the engine and the drive wheels.Because it is a solid continuous connection, power can be transferred in either direction, from the engine to the drive wheels, or from the drive wheels to the engine.
Am automatic transmission uses hydraulic fluid (in the torque converter) to transfer power. This design of the torque converter only allow the power transfer one way. (engine to wheels).
2007-01-19 00:59:12 · answer #1 · answered by fire4511 7 · 3⤊ 0⤋
The short answer is that standard shift cars with a clutch have a mechanical connection between the engine and tires that let's you start by rolling - while the automatic transmission has a fluid connection (torque converter) that slips when the car rolls.
This hasn't always been the case. Earlier automatic transmissions had a rear pump (driven as the rear wheels turned) that at about 35 MPH would provide sufficient flow and pressure as to connect the engine and transmission so the car could be started by rolling.
The auto industry has experimented with all manner of transmissions and drive systems. Chevy, Plymouth, and older Packards and Hudsons had fluid clutches or vacuum operated clutches that operated (in a sense) like automatic transmissions. You'd still shift manually but you'd not use the clutch.
When I was dating my wife before we were married, she'd sit next to me and she'd move the manual shift lever as I let up on the gas. We called it the Pat-o-matic"
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2007-01-19 01:24:23 · answer #2 · answered by james 3 · 1⤊ 0⤋
Standard shift cars have a direct connection from the engine crankshaft through the clutch and transmission. Automatics use a torque converter that operates on hydraulic pressure. The firsts automatics could be push started as they had both front and back pumps
2007-01-19 00:56:00 · answer #3 · answered by Tinman_2_54 2 · 2⤊ 0⤋
Automatic cars have a "liquid clutch" which only come into play at certain ENGINE rpms. If the engine is not turning, there is no pressure connection to the transmission.
2007-01-19 01:02:18 · answer #4 · answered by Lab 7 · 1⤊ 0⤋
Modern automatic transmissions aren't mechanically linked to the engine the way std. trannys are via the clutch. A lot of the old fashioned aotomatics that had a primary hydraulic pump could be push started if you could get them up to about 15 or 20 m.p.h.
2007-01-19 00:58:00 · answer #5 · answered by lurned1 3 · 1⤊ 0⤋
Today's automatics do not have a rear pump, pump driven by the drive shaft. Years ago they did have and you could push jump them however for cost and maintenance reasons they stopped building them. Now when you push them the trans can not build any pressure to turn the engine. Hope this helps.
2007-01-19 00:59:13 · answer #6 · answered by Rick D 2 · 1⤊ 0⤋
It depends on the car for a most cars automatics cost more. But for sports cars manuals cost more. The car company's charge more for the product more people want to have.
2016-05-24 06:37:14 · answer #7 · answered by Anonymous · 0⤊ 0⤋
it has to do with the torque converter in transmission
2007-01-19 00:52:25 · answer #8 · answered by gregs111 6 · 0⤊ 0⤋