synchronized transmissions, trucks vs. tractors

[waugh621]

I recall.seeing a load being tied down using a pipe to lever the binder. It slipped out of the guy's hand, flew over the load, and clocked some poor guy walking by. Yeah, I don't care much for them either.

The reason i dont like them is of 2 stories i've heard. One is a guy i knew useing a pipe to undo on and it slippes and broke out half his teeth and the other was of a guy who was freinds with a buddy of mine who was also undoing a binder and it slipped and he fell off a freight dock. I am all about saving time but i have no intrest in useing those.

 

[showcrop]

That's pretty much what I figured would be happening.

I don't know, if someone was starting away a truck I owned using that method I don't think I would put up with it.

Floating the gears is fine but I don't like that idea at all, especially loaded.

How about if the owner inst

That's pretty much what I figured would be happening.

I don't know, if someone was starting away a truck I owned using that method I don't think I would put up with it.

Floating the gears is fine but I don't like that idea at all, especially loaded.

Try reading my explanation again.

 

[showcrop]

The idea is to change gears when the teeth of the gears are matching in speed. To get there, the clutch is pushed in and the trans put in neutral, the clutch is let up while the engine is brought to the speed that the truck/tractor/car would be when that next gear was slid in place. The clutch is then pushed in and the shifter selects that gear. The speed match is thus limiting the clashing of the gears as it is shifted. when the clutch is let out the engine speed is close to that gear's ground speed and things are smooth and not jerky. In tractors the difference in gear ratios from adjacent speeds is pretty wide, and the engine is often equipped with a heavy flywheel that doesn't allow it to be adjusted to the expected speed quickly. This works in a truck or old car going up in ratio, or down to lower gears. It is easier because the gas pedal allows hands free adjustment of engine speed and the engine is often quicker in response both slowing down or speeding up to accommodate the next ratio.
Motor Cycle Trans
Motorcycle transmissions have sliding gears with holes and projections that allow the gears to be selected by locking them to a shaft. I have never seen a syncro in a motorcycle trans. See video. Shifting a motorcycle without the clutch is not recommended because it wears out the engagement dogs and holes when forced to disengage and engage under load.

Float shifting is done without the clutch by the experienced operator (not from a standing start) and is done by lifting the throttle till the transmission/drive train has little or no power flowing through it then shifting out of gear as this takes place. then revving the engine on a downshift, or slowing the engine on an upshift so the gear tooth speeds match closely with the gear being selected then the shifter is moved rapidly into gear (no or little load is on the gears. The power is reapplied, or removed if using compression braking, to resume the link between the driver's intent and the vehicle. I have driven hundreds of miles floating the gears in trucks and cars. Jim

When I was first driving trucks as a teen, I thought that double clutching was a thing. I was away from trucks for awhile and when I got into heavier trucks there was no double clutching going on. I don't know why anyone would.

 

[showcrop]

I don’t get the question. Under what circumstances would you want to go from a dead stop without using the clutch… unless the pin fell out of the pull rod… in that case you would shut it off and put it in gear and start the motor.

As a few of us have already posted. Pain. Do you go looking for pain???

 

[Brown David]

How about if the owner inst

Try reading my explanation again.

I understood your explanation completely.

Just not something I would do.

 

[moresmoke]

Barnyard, you definitely poked the hornets nest here. I agree with the others that the medium duty synco 5-6-7 speed transmissions shift like garbage. Now none of these guys have driven a class 8 truck with a synchro box. The Europeans have had them for decades. The family truck business i grew up around was not afraid to try a few different things. We had a couple Scania trucks and quite a few Volvos with synchronized transmissions. Air assist clutch, and some had air assist shift. One finger could push the clutch pedal down or move the shift lever. The latest of the Volvos were a 14 speed, driving you used 3 slots with high and low range, plus a split in each that you just lifted off the throttle to shift.

One of those Scanias was a short day cab used as yard jockey. All it did was get shifted all day. I think it got 3 clutches in 35000 hours. It got shipped to South America when the frame was too rotten to pass inspection.

I would take one of the Euro synchro boxes any day over an American heavy truck transmission, and yes I drove over the road for about 10 years.

On the topic of double clutching, you can shift faster in tough conditions by double clutching, ie mud, soft fields, starting out on steep grades etc. But as others said, American clutches are tough on the joints, so not something you want to do all the time.

Currently, I have a Volvo with an automated 12 speed, it is not bad, there are a number of settings that can be programmed, starting gear, skip shifting, also, the dealer can load different software packages for specific uses that give the transmission a different personality. I would not want to drive it with out the manual override option where the driver can select the desired gear for specific conditions. I added that to my truck. I probably would not have bought the auto, but the wife said she would not drive without it.

 

[J Hamilton]

Barnyard, you definitely poked the hornets nest here. I agree with the others that the medium duty synco 5-6-7 speed transmissions shift like garbage. Now none of these guys have driven a class 8 truck with a synchro box. The Europeans have had them for decades. The family truck business i grew up around was not afraid to try a few different things. We had a couple Scania trucks and quite a few Volvos with synchronized transmissions. Air assist clutch, and some had air assist shift. One finger could push the clutch pedal down or move the shift lever. The latest of the Volvos were a 14 speed, driving you used 3 slots with high and low range, plus a split in each that you just lifted off the throttle to shift.

One of those Scanias was a short day cab used as yard jockey. All it did was get shifted all day. I think it got 3 clutches in 35000 hours. It got shipped to South America when the frame was too rotten to pass inspection.

I would take one of the Euro synchro boxes any day over an American heavy truck transmission, and yes I drove over the road for about 10 years.

On the topic of double clutching, you can shift faster in tough conditions by double clutching, ie mud, soft fields, starting out on steep grades etc. But as others said, American clutches are tough on the joints, so not something you want to do all the time.

Currently, I have a Volvo with an automated 12 speed, it is not bad, there are a number of settings that can be programmed, starting gear, skip shifting, also, the dealer can load different software packages for specific uses that give the transmission a different personality. I would not want to drive it with out the manual override option where the driver can select the desired gear for specific conditions. I added that to my truck. I probably would not have bought the auto, but the wife said she would not drive without it.

View attachment 65678

I drive a very similar truck at work, 2018 Mack with the M-Drive 12 speed. Like you said, you can more or less "personalize" the shift points to your driving conditions. Didn't think I would like the auto, but it is pretty nice. Although I prefer a manual for some jobs like pulling a tanker. Which is why I talked my company into keeping "old faithful" 1986 Mack R-600 with a 9 speed especially for when I have to pull out tank, which is a smooth bore.

 

[MarkB_MI]

The ability to shift a non-synchronized transmission is highly over-rated. Pretty much anyone can learn how in a few minutes.

When I was in Egypt, I had a driver/translator who drove me to and from work every day. One morning as I come out of my apartment, he tells me the clutch isn't working in the Renault station wagon he's driving and we'll need to get a different car. I don't want to wait for a replacement car, so I told him to just drive it without the clutch. He didn't believe it was possible so I said I'd drive. I took the wheel and drove to work in the bananas Cairo traffic and explained to him how to shift without the clutch. Halfway to work we switched places and he quickly learned how to drive with no clutch. By the time we got to the Egyptian army base where I worked, he was shifting like an old pro.

 

[deeretails]

Just a comment, I recently bought a John Deere 2020, the manual instructs on how to double clutch to shift. It does not have synchros.

 

[john in la]

John did you read my explanation on how it is done? there is no jamming involved

Showcrop
I did read your explanation even though I did not have to.
I know exactly how it works and have done it many times.

With that said the word we use in the English language to describe putting one stationary piece into a moving piece is "Jamming"

 

[Hemmjo]

I am a bit surprised that no one has mentioned the far that there are different types of transmissions in use in all of the various types of vehicles mentioned. Farm tractors, OTR trucks, an XK-E type auto, motorcycles. There are sliding mesh, constant mesh, syncro-mesh and some with a combination inside a single box. There are also transmissions with planetary gear sets. These are typically automatic transmissions, like the Allison.

Sticking with the manual type;

Sliding mesh, the gears slide along shafts and the actual teeth of the gears move into and out of contact with their partner as required. My old Ford 860 has this type.

Constant mesh, all of the various gears combinations are in constant contact and all are spinning on there respective shafts all the time. The power is transmitted through the desired gears by sliding "dogs" that lock the desires gears to there shafts. Most motorcycles, Outboard forward/reverse. and I am thinking most OTR trucks.

Syncro-mesh, like constant mesh, with the exception there is actually a little cone type clutch on each shift dog that engages to do the work of speed matching before the dog engages the gear. Most manual transmission passenger cars and light duty trucks.

Each type has its advantages. Whether the advantage is purely production cost, operational cost, performance, long term reliability, or a combination of those factors.

I have had lots of transmissions apart over the years, but never an OTR type. I know from experience that motorcycles typically do NOT have syncronizers. They are typicially a constand mesh "dog box" where shisting is controlled by a rotating cam type shifter that "slams" the dog into the desired gear. Thus the solid "clunk" then you kick one into gear. Typicially only clutched to start/stop. Skilled riders do float the throttle when shifting. Racing riders just slam them from gear to gear.

The XKE my old '60 chevy and most other early manual shift cars, had sliding mesh first and reverse, the other gears were syncronized. The logic being you had to stop anyway to get into reverse, and you seldom need first gear unless you are already stopped. It you had to have first gear before you stopped, you had to learn to double cutch.

Havng never had an OTR transmission apart, I can stilll see where syncronizers would be a bad idea in them. The syncronizers in a manual transmissiom are the most common point of failure. Each syncro, for each gear is a little clutch. That little clutch has to get all of the rotating mass going at the proper speed in order to get into the proper gear. That is a lot to ask considering inertia of the rotating mass of just the BIG truck clutch disk then add heavy iron gear itself. Syncronizers also take up space. When you are trying to stuff more gears into a box, space is important. OTR drivers SHOULD be more skilled than most drivers, so they are able to elimimate the troublesome syncornizers and replace them with with more gears and some easy to master skills.

Just some thoughts on the topic/

 

[Fritz Maurer]

Actually, the Fuller 9505 and RT-613 both have synchros in them.

 

[4wdtom]

You have a very basic mis-understanding here. Though it is true that you need to have your road speed and transmission speed correct to make the shift, it is not anything significant. Within a very few hours of starting to drive a different truck/engine/transmission/load, combination, you are shifting without thought. You're not matching up anything except your tires to the lines. Not using the clutch when shifting a synchroed transmission will quickly wear the synchros out, ruining the transmission. "Floating" the gears is obviously faster than clutching because you are eliminating both dis-engagement and engagement of the clutch. Heavy truck clutches have double discs, with double the spring force, so they take double the pedal effort. Shifting them using the clutch is hard on the knee, which results in pain. Do you seek after pain? Given the choice I would take an automatic. I have a lot of miles through a lot of traffic lights and stop signs with heavy spec Macks. One an auto and the other a 13 speed. I have had times of over 200 stops per day driving a Mack duplex. Just starting and stopping was painful, let alone shifting between gears. On the second day the owner taught me how to stop and start without using the clutch. It is legitimate and in no way abusive of the truck.

I would be interested how you start without using the clutch. I can see stopping by just slipping it into neutral with no load on the drive train, but starting??

 

[showcrop]

I would be interested how you start without using the clutch. I can see stopping by just slipping it into neutral with no load on the drive train, but starting??

I posted the complete procedure earlier. I thought that it was clear but most readers can't believe it, so let me just emphasize again that it involves nothing detrimental to the truck

 

[J.Wondergem]

I've always found it odd that tractors without synchronized transmissions are considered "backward" while commercial trucking has universally and permanently rejected them. There are two contradicting "truths" about synchronized transmissions:

1. You're not a "real trucker" unless you're double-clutching and/or floating gears.

2. You don't have a "real tractor" unless it has synchronized shifting.

The excuse for truckers I heard is that the synchronizers don't last in commercial trucks. That's a 100 year old excuse. Tractors have had robust synchronizers since 1960. Surely someone has come up with an even more robust synchronizer for commercial trucking. Why are truckers so bent on suffering?

My 1969 Kenworth with a Spicer 4x4 had synchronizers in it.

 

[showcrop]

Showcrop
I did read your explanation even though I did not have to.
I know exactly how it works and have done it many times.

With that said the word we use in the English language to describe putting one stationary piece into a moving piece is "Jamming"

John you still do not get it. I am honestly surprised.

 

[495man]

I've always found it odd that tractors without synchronized transmissions are considered "backward" while commercial trucking has universally and permanently rejected them. There are two contradicting "truths" about synchronized transmissions:

1. You're not a "real trucker" unless you're double-clutching and/or floating gears.

2. You don't have a "real tractor" unless it has synchronized shifting.

The excuse for truckers I heard is that the synchronizers don't last in commercial trucks. That's a 100 year old excuse. Tractors have had robust synchronizers since 1960. Surely someone has come up with an even more robust synchronizer for commercial trucking. Why are truckers so bent on suffering?

Hmm. As luck would have it, I don't have to my reply again.

Synchromesh in farming vs. trucking

Why is it that "synchromesh is for female cats" if you're a truck driver, yet it is a MUST in farm tractors? Over and over I see these complaints about certain tractors not having synchronized transmissions, and how they were junk and no good and behind the times... Yet to this day, you...

forums.yesterdaystractors.com

My answer is still the same. I still drive both sync and unsync transmissions. I want synchromesh for field work. I am happy with either with road work.

 

[wore out]

Barnyard,
Would you believe my 1962 jag xke was both.
First gear wasn't synchronized, the rest of the tranny was.
You had to be stopped to put it into first gear.
I think this was so when they were racing, you couldn't accidentally downshift into first gear and possibly blow up the engine.

Heck, my 'ol '53 GMC and '57 Chevy trucks don't have a synchronized 1st gear , either, but the other 3 forward gears are!

 

[cjunrau]

Unfortunately, the so-called "automatics" that they put in big trucks today are less than desirable. There are still a lot of bugs to be worked out. They are actually manual transmissions that are operated by computer. That includes the clutch. There are a lot of things about them that I do not like.
One thing is the shifting. They use every gear whether the truck is loaded, empty, or bobtail. another thing is the clutch engagement. Try backing into a dock with one and not slam the dock. Nearly impossible. When you are about a foot away, and you need just that little bit, the clutch will not start to engage until you give it some throttle. Then, it engages abruptly and slams into the dock. On hills, it lugs down the engine too much before downshifting. All in all, a real pain in the neck.

The new auto trucks you can hold your foot just a little on the brake and slowely back into a dock. i own the 3 pedal and like it but my fiend has the real auto and it has a torque coverter or something like that in first and reverse. he says it works as good as his pick up truck. once on the road it shifts like a standard. He is worried if he ever has to fix it will cost a lot to fix and he might not have the computer knowledge to fix it.

 

[marloweg]

this is why trucks are not trucks anymore they had to put autos in them so all the so called truck drivers could drive them .can't even buy a manual trans in a pickup anymore