bl@hplabsb.UUCP (11/14/85)
Why do cars (i.e., motor vehicles) have clutches? Hint, it's NOT so you can shift gears.
msg@drutx.UUCP (GrahamM) (11/16/85)
Why do cars have clutches? Because, the engine has to keep running while the car starts from a stop. A clutch enables the engine to do this. It is inconceivable to me how an engine directly coupled to the wheels could get the car moving from a dead stop without the assistance of a starter, but that would be too great a strain on the battery, and wouldn't work as well as with a clutch. But then, what do I know? Matt Graham !ihnp4!drutx!msg
ems@amdahl.UUCP (ems) (11/16/85)
> Why do cars (i.e., motor vehicles) have clutches? Hint, it's NOT so you > can shift gears. Is it not so that you can turn the crank to start them without getting run over? -- E. Michael Smith ...!{hplabs,ihnp4,amd,nsc}!amdahl!ems 'If you can dream it, you can do it' Walt Disney This is the obligatory disclaimer of everything. (Including but not limited to: typos, spelling, diction, logic, and nuclear war)
ron@brl-sem.ARPA (Ron Natalie <ron>) (11/16/85)
> Why do cars (i.e., motor vehicles) have clutches? Hint, it's NOT so you > can shift gears. Well, I've always found it convenient to be able to stop the wheels without stopping the engine as well. -Ron
daw1@mhuxl.UUCP (WILLIAMS) (11/18/85)
> > Why do cars have clutches? > My Camaro has one so I can tach it up to about 5 grand to ensure gas is pouring through all four bbls., drop the clutch and smoke up the rear tires. Ah, nothing like the sound of a small block Chevy screaming as it sucks in good clean air and replaces it with the exquisite smell of molten rubber :-) Doug
pwv@fluke.UUCP (Pat Vilbrandt) (11/18/85)
> Why do cars (i.e., motor vehicles) have clutches? Hint, it's NOT so you > can shift gears. Outside of the obvious answer that the engine would quit when you stop, the real reason is that an internal combustion engine produces torque that is relatively proprotional to engine rpm (up to a point). At low rpm (idle) the engine is producing very little torque. You need a "clutch" (the torque converter in an automatic transmission) to allow the rpm to increase to a point to where the engine is producing enough torque to move the car. An external combustion engine (ie. steam engine) can produce full torque at zero rpm, so you don't see clutches on old steam locomotives. Electric motors (depending on drive electronics) can also be made to put out enough torque at zero rpm that a clutch isn't needed to start up an electric car. -- Pat Vilbrandt John Fluke Mfg. Co., Inc. Everett, Washington USA UUCP: { decvax!uw-beaver, ucbvax!lbl-csam, allegra, ssc-vax, decwrl!sun }!fluke!pwv ARPA: fluke!pwv@uw-beaver.ARPA
bl@hplabsb.UUCP (Bruce T. Lowerre) (11/19/85)
> Why do cars have clutches? > > Because, the engine has to keep running while the car starts from a stop. > A clutch enables the engine to do this. It is inconceivable to me how an > engine directly coupled to the wheels could get the car moving from a > dead stop without the assistance of a starter, but that would be too > great a strain on the battery, and wouldn't work as well as with a clutch. > > But then, what do I know? > > Matt Graham > !ihnp4!drutx!msg Correct! Gasoline and Diesel engines have zero starting torque.
marauder@fluke.UUCP (Bill Landsborough) (11/21/85)
In article <321@mhuxl.UUCP> daw1@mhuxl.UUCP (WILLIAMS) writes: >> >> Why do cars have clutches? Actually the clutch is there so that you can sit on a steep hill waiting for the light to turn green and not have to bother with putting on the brake................... 8*( Its also a neat place to rest your left foot while driving.
spw2562@ritcv.UUCP (11/21/85)
In article <3173@hplabsb.UUCP> bl@hplabsb.UUCP writes: >Why do cars (i.e., motor vehicles) have clutches? Hint, it's NOT so you >can shift gears. Granted, you don't NEED a clutch to shift, but it sure makes it easier/quicker/smoother/less wear and tear. ============================================================================== Steve Wall [Snoopy] @ Rochester Institute of Technology USnail: 6675 Crosby Rd, Lockport, NY 14094, USA Usenet: ...!ritcv!spw2562 Unix 4.2 BSD BITNET: SPW2562@RITVAXC VAX/VMS 4.2 Voice: Yell "Hey Steve!" Disclaimer: What I just said may or may not have anything to do with what I meant to say...
bcking@inmet.UUCP (11/23/85)
** ** So your left foot won't feel left out? R.M. Mottola Cyborg Corp. Newton, MA.
rickb@tekig4.UUCP (Rick Bensene) (11/23/85)
> In article <321@mhuxl.UUCP> daw1@mhuxl.UUCP (WILLIAMS) writes: > >> Why do cars have clutches? > Actually the clutch is there so that you can sit on a steep hill > waiting for the light to turn green and not have to bother with > putting on the brake............ > ---> Its also a neat place to rest your left foot while driving. <--- If you *DO* actually rest your foot on the clutch pedal while driving, you might as well forget about any life from your clutch disk and throwout bearing. It's been proven that resting your foot on the clutch pedal, even lightly, will cause decreased clutch and throwout bearing life due to the pressure on them from the amplified pressure of your foot on the pedal. So, if it's a habit, break it, or else, go buy a car with an automatic! (Then you'll probably ride the brakes... |-}) Rick. ------------ Rick Bensene {ihnp4, decvax, allegra, cbosg, ucbvax}!tektronix!tekig4!rickb Phone: Weekdays (503) 627-3559 BBS: (503) 254-0458 300/1200 baud, 24 hours a day US Mail: Tektronix, Inc. - P.O. Box 500, Mail Stop 39-170 - Beaverton, Oregon 97077
wjh@bonnie.UUCP (Bill Hery) (11/23/85)
> > Why do cars have clutches? > > > > Because, the engine has to keep running while the car starts from a stop. > > Correct! Gasoline and Diesel engines have zero starting torque. Not a correct answer to the original question, which asked for the reason NOT INCLUDING SHIFTING GEARS. This solution seems to refer to the need to shift into neutral for starting. Can the original poster respond with the correct answer (assuming that this isn't it)
jeq@ihwpt.UUCP (j quist) (11/23/85)
> Why do cars have clutches? > > Because, the engine has to keep running while the car starts from a stop. > A clutch enables the engine to do this. It is inconceivable to me how an > engine directly coupled to the wheels could get the car moving from a > dead stop without the assistance of a starter, but that would be too > great a strain on the battery, and wouldn't work as well as with a clutch. 8 or 10 years ago the clutch cable broke in my father's 1972 Capri. Solution? He let the engine warm up quite a while, and then started the engine with the transmission in 1st gear. He said it worked fine, but made for a rather rough ride (as well as lots of nasty looks) until he got out of downtown Chicago and onto the expressway! Of course, if you don't know how to shift without the clutch (it takes lots of practice), the repairs to you gearbox can cost more than a tow. :') Jonathan E. Quist Lachman Associates Inc. @ AT&T Bell Laboratories ihnp4!ihwpt!jeq
levy@ttrdc.UUCP (Daniel R. Levy) (11/24/85)
In article <635@bonnie.UUCP>, wjh@bonnie.UUCP (Bill Hery) writes: >> > Why do cars have clutches? >> > >> > Because, the engine has to keep running while the car starts from a stop. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ >> >> Correct! Gasoline and Diesel engines have zero starting torque. > >Not a correct answer to the original question, which asked for the >reason NOT INCLUDING SHIFTING GEARS. This solution seems to refer ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ >to the need to shift into neutral for starting. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Oh, does it??? When the auto starts from a standstill (with the engine running first) the clutch is acting as a lossy coupling as it is brought greadually into engagement. The car could stay in first gear, say, during this startup process; no need to shift at all. The clutch's purpose is, in this light, obvious; a way to connect the engine to the rest of the drivetrain when desired, and to disconnect it when desired, incidentally providing a (we hope) smooth transition in between inde- pendent of any gear ratio that might be selected. It is only because of the way that gearing is usually implemented that it proves necessary to disengage the clutch while changing gear ratios. If your "gearing" is something like a belt drive on a variable diameter pulley system, then it becomes unnecessary to disengage the clutch, except when bringing the car to a stop (or changing directions) without doing likewise with the engine. (In this wise, I also protest the original poster's assertion that it was not for shifting gears. It IS, if you shift from forward to reverse and don't have an engine that can do the same! It would be a mighty tricky implementation of a gear system to allow THAT without ever disengaging the engine, short of incorporating a slipping coupling, which could then be argued to act as a clutch anyway.) -- ------------------------------- Disclaimer: The views contained herein are | dan levy | yvel nad | my own and are not at all those of my em- | an engihacker @ | ployer or the administrator of any computer | at&t computer systems division | upon which I may hack. | skokie, illinois | -------------------------------- Path: ..!ihnp4!ttrdc!levy
msg@drutx.UUCP (GrahamM) (11/25/85)
>>> > Why do cars have clutches? >>> > >>> > Because, the engine has to keep running while the car starts from a stop. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ >>> >>> Correct! Gasoline and Diesel engines have zero starting torque. >> >>Not a correct answer to the original question, which asked for the >>reason NOT INCLUDING SHIFTING GEARS. This solution seems to refer > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ >>to the need to shift into neutral for starting. > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > >Oh, does it??? When the auto starts from a standstill (with the >engine running first) the clutch is acting as a lossy coupling as it >is brought greadually into engagement. The car could stay in first gear, >say, during this startup process; no need to shift at all. ... > > dan levy | yvel nad | my own and are not at all those of my em- Dan has rightly stated what I should have in my posted answer. I was thinking of starting from a stop with the car in gear. Matter settled. Regards, Matt Graham !ihnp4!drutx!msg
ron@brl-sem.ARPA (Ron Natalie <ron>) (11/26/85)
> > > Why do cars have clutches? > > > > > > Because, the engine has to keep running while the car starts from a stop. > > > > Correct! Gasoline and Diesel engines have zero starting torque. > > Not a correct answer to the original question, which asked for the > reason NOT INCLUDING SHIFTING GEARS. This solution seems to refer > to the need to shift into neutral for starting. Can the original > poster respond with the correct answer (assuming that this isn't it) Eh? Shifting gears is an all or nothing proposition. You can't gradually trasfer the load of the engine by shifting from neutral to first no matter how you do it. If you do manage, you are wearing your gear like it was the clutch. You need the clutch to START the wheels turning since the engine won't develop any torque when coming from a dead stop. Once you are moving, you don't need the clutch. On most manual transmissions if you shift at the right speed, you will do a very smooth shift even if you don't touch the clutch. This doesn't extend to the 18 ton trucks that I've driven though, too much load on the transmission I guess. -Ron
paul@ubvax.UUCP (Paul Fries) (11/27/85)
In article <635@bonnie.UUCP> wjh@bonnie.UUCP (Bill Hery) writes: >> > Why do cars have clutches? >> > >> > Because, the engine has to keep running while the car starts from a stop. >> >> Correct! Gasoline and Diesel engines have zero starting torque. > >Not a correct answer to the original question, which asked for the >reason NOT INCLUDING SHIFTING GEARS. This solution seems to refer >to the need to shift into neutral for starting. Can the original >poster respond with the correct answer (assuming that this isn't it) I must disagree with this analysis. Consider a car with ONLY ONE GEAR THAT IS ALWAYS ENGAGED. Even though you cannot shift this beast, you still would like a clutch for starting the car from standing still. If this is not a practical enough example, consider a beast that was seen on the drag racing circuit a few years ago. It was a fuel dragster that was equiped with a LENCO two-speed planetary transmission (I might be wrong about the name "LENCO", but that is not really important). This transmission was similar to the planetary arrangement found in an automatic transmission, except that it was manually (as opposed to hydraulically) operated. The point is that there was no neutral; the gears were always engaged, and shifting the thing did not involve the clutch. The vehicle was still equiped with a clutch so that it could sit at the starting line with the engine running. What it boils down to is that the clutch is really only necessary to get the car moving from standing still because internal combustion engines (including diesels) have zero starting torque. All the other uses of a clutch can be handled by other means, but there must be something to disconnect the engine from the wheels so you can stop the vehicle with the engine running.
spw2562@ritcv.UUCP (Snoopy) (11/29/85)
In article <603@ttrdc.UUCP> levy@ttrdc.UUCP (Daniel R. Levy) writes: > The clutch's >purpose is, in this light, obvious; a way to connect the engine to the >rest of the drivetrain when desired, and to disconnect it when desired, This can be done by shifting in and out of neutral. Shifting into neutral is easy, out of neutral can be done IF the can is moving. Getting it out of neutral(into gear) while the engine is running and the car is stopped is a problem. It would require meshing a moving gear with a non-moving gear. With a cluth, the engine side gear doesn't have to be moving, and then you'd be meshing two non-moving gears. Easy. Otherwise, you'd have to get the engine down to zero RPM's, and still have it running.. ??? It wouldn't have any torque then, and couldn't move the car. Slipping the clutch into engagement lets you start the engine side gear moving while keeping the engine torque up. As per someone else's posting. > It IS, if you shift from forward to >reverse and don't have an engine that can do the same! Wrongo. shift to neutral, brake the car, shift to reverse. But then, see my above statement. I think we're beating this stupid discussion to death.. 8-) ============================================================================== Steve Wall [Snoopy] @ Rochester Institute of Technology USnail: 6675 Crosby Rd, Lockport, NY 14094, USA Usenet: ...!ritcv!spw2562 Unix 4.2 BSD BITNET: SPW2562@RITVAXC VAX/VMS 4.2 Voice: Yell "Hey Steve!" Disclaimer: What I just said may or may not have anything to do with what I was actually thinking...
smh@mhuxl.UUCP (henning) (12/03/85)
**** **** From the keys of Steve Henning, AT&T Bell Labs, Reading, PA mhuxl!smh > What it boils down to is that the clutch is really only necessary to > get the car moving from standing still because internal combustion > engines (including diesels) have zero starting torque. When the hydraulic clutch on my A-H Sprite failed, I found out that I didn't really need a clutch. Most cars have an item called a starter which gives the engine torque at 0 RPM. In fact I had enough torque to start the car in 2nd gear every time I came to a stop sign or red light and couldn't creep through it. The only reason I can think of for having a clutch is so you can repair it rather than the transmission and the starter motor.