single clutch

I have heard of the term "single clutching". Have never had it adequately explained. But was told if done right, a driver is less likely to miss a gear. DOT likes that for crossing train tracks and moving through intersections and such. And Yase12278 is correct....most examiners will fail you for not using the clutch while shifting. And that is why some schools are teaching single clutching. So a newbie can pass the test easier. Missing too many gears can fail ya too.

 

I will have to say Yase, it was a long, long time ago. I took my test in a R model mack duplex. I don't think they make them any more or a triplex. lol

 

FWIW, the company that my brother drives for in So. Cal sent him to a fly by night "truck driving course" to get his class B. Not sure about all the details but apparently they trained in a truck that had synchronized transmissions and when he got in his new (to him) Sterling he called me up because his could not shift. Talk about a rip off........

 

I have a question. I am somewhat ignorant about clutching a semi, as I have not driven one. I have heard repeatedly it is not like a 4 wheel. Well, I've been driving manuals in 4 wheels since I was a teenager (I'm 53). From a 3 on the tree in an old chevy truck where ya got to fiddle the shifter just right to get it to go up into second and with the synchro-mesh pretty worn out, to hot rods with 4 on the floor spring loaded clutches that wear your left leg out going through 5 miles of traffic to the ease of hydraulic clutches. Anyway, in a 4 wheel I'll usually push the clutch while taking the tranny out of it's existing gear, allow the RPM of the engine to slow down or else tap the gas to increase the RPM, in order to match the engine speed to transmission speed and the tranny will slip into the gear I want. Then I'll let the clutch out. In performing a double-clutch, what is the purpose of letting the clutch out while you are in neutral? How does that help synch the speed of the engine and transmission? I am just curious as I understand the necessity of matching the engine speed to the tranny speed, but I don't understand how double clutching helps that to happen, over only clutching once. Appreciate an explanation. Thanks

 

Synchronized is the magic word.

Most transmissions have synchronized gears, which means that the gear speeds match when you depress the clutch once.
But that adds a level of complexity, by way of the syncro gears.

Trucks don't have these extra gears, probably because they are the weakest link and tend to wear out more quickly.
Also, with so many gears and stages (hi, low and otherwise) it would add too much complexity and cost.

 

I think I may have it figured out. Please correct me if I have it wrong. When you have the clutch engaged (pedal depressed) and the tranny is in neutral, the tranny input shaft is basically free-spinning. Synchro gears will, in a 4 wheel tranny, synchronize the speed of the output shaft with the input shaft. The purpose of letting the clutch out while your in neutral is to 'force' the input shaft to spin at the speed of the engine, since there are no synchro gears to do it, and when the speed of the input shaft and output shaft match the gear you wish to shift into, depressing the clutch and slipping it into gear should happen easily. Is that it?

 

I had to triple clutch on my test.

 

I occasionally (rarely) use the clutch to break torque going out of a gear and float back into the next. Usually when downshifting rather than bumping the throttle to get it out. Is that single clutching?

 

The purpose of double clutching is to sync the tranny with the engine. It can be done by single clutching or no clutching at all provided you are in motion. Floating is the easiest way to do this however most companies want to see that you know how to double clutch and also when taking the state exam they will want you to use the clutch. I have never heard of single clutching during the exam but that doesn't mean some don't accept it.

In reality it all comes down to timing. When the motor, and tranny are spinning at the same speeds then you will be able to drop it in a gear.

 

Six9Gs you got it, however if you learn how to shift without a clutch, much better off. You cannot do this however with a 4 wheeler. You'll tear up the sincros. It's like great sex, your touch and feel and the reaction you get back, gives you your next reaction. lol