Monday, July 20, 2009

Improvements in Trucking Technology

Og (the Neanderpundit) had a post the other day where he discussed how technology has improved certain things, while for nostalgia's sake, some things remain timeless. Roberta's penchant for retrotech inspired his post. Og asked what his readers' preferences were. My answer was trucking related and I'd like to expound on it here, now that I've got some time. We're finally picking up, and the tubby trucker has been a travelin' man lately - too tired for a substantial post.

When I started driving twenty five years ago, trucks looked pretty much the same as they do now, but I can assure you there are major differences. The powerplants are similar in that they are large displacement diesel motors, but their fuel management is far different. Older motors had mechanical fuel injection - Caterpillar's used a fuel pump that precisely metered the fuel charge to each injector, and most of the rest used a common rail - where fuel was pumped to a certain pressure and the injector was timed to release a certain amount of fuel. Now, it's all electrically managed by a computer. Timing the injection can be altered. Some of the earlier motors could do that mechanically, but not in response to real time conditions, plus there was added complexity and thus added costs to maintain.

You can see I'm leaning towards today's electronically managed motors, and you'd be right. The older motors could be repaired by a shade tree mechanic, they could be "modified" to put out more power, and they sounded pretty good. Newer motors sound like washing machines and dryers. They start much easier in adverse conditions, make better fuel mileage (until the last round of eco rules, anyways), can be made idiot proof for fleets and so much more. It's a waste of time letting the Cat I drive go beyond 1700rpm - it pulls far better at lower rpms. My fav Cummins would have melted down turning so slow - it liked 2100 a lot better. I've mentioned this before considering "Which Diesel is Best" a while ago. But, there is a trade off - the complexity and the planned obsolescence inherent in the direction the industry has taken assures that in years to come the lack of parts and the improvements in technology will make these motors boat anchors. They won't be worth fixing.

Tech improvements haven't been in engine management alone. Another big improvement has been in suspensions. Most older suspensions are variations on leaf springs. Most common is the Reyco style, often called a four spring - and while just about all suspension brands make this variety, Reyco is to this style as Kleenex is to facial tissue.

This is a representation of a trailer suspension, but this was also used on the drive axles of tractors as well. This was probably the most common, and the most "comfortable" of the leaf spring varieties. It wasn't very good on extremely rough ground - the center rocker would allow one axle to raise or lower a limited amount. Wheels often were lifted clear of the surface - not a good thing with drive axles. The free wheel would spin, and the truck was "stuck."

So, there was another style - the Hendrickson or "walking beam."

The axles mounted to the beam can "walk" over uneven ground far better than with a Reyco with the side effect of a very rough ride. That big stack of leaves just didn't give much. Mack trucks have used their own variant referred to as the Camelback suspension. It's pretty much the same as the Hendrickson, but with this kind of leaf array:

This is reminiscent of a camel's hump - thus the name. The advantage of turning the spring over is to lower the frame of the trailer or truck while allowing the same ground clearance. Tough? Yep. Long term effects on a driver's lower back? Not so good.

There is another style of suspension that bears mentioning - the torsion bar:

There were several varieties - this one has the "tension" in the shackles. Some had arms hooked to a steel bar mounted lengthwise along the frame - the suspension would force the bar to twist as the axles moved. Kenworth (IIRC) used that variety. Supposedly, if it was set up and maintained correctly the ride was pretty good.

All of these various suspensions are still sold and serviced, but the air ride (technically air spring) suspensions have taken over the market. For good reason - they ride better. Much better. The first benefit that comes to my mind is driver comfort - but there are other advantages. Older trucks eventually are just beaten apart by the rough miles. Maintenance costs across the board are less as a result of using air ride. Cargo is delivered with less damage due to trailers bouncing off the ground when hitting potholes. This is the most common style:

This is a trailer suspension - not only are there four air springs, there are four torque arms and two locating arms, plus four shock absorbers. Far, far better than bare springs.

This is Peterbilt's new Flex Air - you can see the yellow curved springs will allow further movement in response to rough roads.

This is Kenworth's latest variation of their "Eight Bagger" suspension. It's heavier than the four bag variety, and opinions are mixed as to the ride effectiveness. I can tell you KWs feel more "tippy" while cornering with this suspension. It's just another thing to get used to driving different brands of trucks.

Not only have the suspensions gone to air, but the cabs are suspended as well. Usually, the cab pivots on two bushings mounted to the frame at the firewall and have a small air spring under the rear, as well as a shock absorber. This has led to a more complex shift lever - in the old trucks, the shift lever was fixed to the tranny through the top gates. Now, the lever rides with the cab. If the lever was still directly attached to the transmission, it would appear to be bobbing and weaving in the cab all the time. Might be kinda hard to shift, and it might hurt if your hand was in the wrong place at the wrong time. This development has led to cabs lasting much longer. A lot of the old cabover trucks would literally split in certain high stress areas. Don't believe me? If you can find an old Freightliner cabover, look at the upper corners of the radiator opening. If it has any miles at all on it, the aluminum will have a large stress crack.

The NVH (Noise Vibration and Harshness) of cabs has come a long way, baybee. Doors can be shut without a windup like a pitcher in baseball, slamming them home just to close 'em. There are less rattles - but with plastics there are a fair amount of squeaks, irritatingly enough. But you can hear those squeaks, not like in the old cabs. When the windows are rolled up, it's pretty quiet in today's OTR rigs.

HVAC has also improved markedly. Everyone's favorite classic - the 359 Pete - only had two registers on top of the dash to cool or heat you, defrost the windows, or whatever. They were amazingly adjustable, but there wasn't a lot of air. In the 9900i I drive there are four separate dash registers, long slits along the windshield for the defroster, and several heater registers. The fans move a lot of air, too.

Most trucks come with compression brakes (aka "Jake" brakes) and cruise control. The electronic management revolution has also improved the old Jake brake - they actually do something other than just make noise - they really help brake a truck. While the old Jakes helped, the weren't as effective as today's. The new higher horsepower Cummins ISX motors have a 600hp brake rating, even if the motor isn't rated that high for power. The ACERT Cat I drive now can be run one gear higher than the older C15s I've driven dropping off "The Hill" (the Rockies). And they worked far better than the old mechanical motors. Cruise control has made a huge difference in driver comfort. Back when my bladder could take it, I'd drive five hours straight - but my knees were so stiff it was a toss up whether I'd fall out or step out of the cab. Not a problem these days.

These are examples of "Dayton" wheels. The center is a cast web design, and the rim is two or three piece steel. The wheel fits on curved pads at the end of the spokes, and the rims are held by L shaped wedges fixed by a nut. Dual wheels are on wider hubs with a spacer ring between the two wheel rims. All these pieces and parts don't always go on straight - I'm sure some of you have seen some old truck driving down the road with wobbling wheels. So, triple digit speeds with these babies is a risky proposition. That isn't the half of it - the rims are "split." Which means they consist of two or three pieces. Both examples here are two piece rims - you can see the splits at about the seven o'clock position. When the tire is broken down, the split ring has to be hammered loose then pried out so the tire (and tube - these puppies can't be tubeless at all) can be removed and patched or replaced. When they are reassembled, it's a damn good idea to put them in a "cage" - a structure made of steel pipe designed to hold in the parts if they decide to "blow." If the ring doesn't catch just right, the air pressure will force it out of position, often at a high rate of speed. I've seen cages made of some pretty serious pipe bent up pretty good from one of these old rims letting go. I don't miss these things at all.

They were mostly supplanted by Budd style wheels with their unique fasteners.

Budd wheels are "hub piloted" which means the hub is the centering mechanism. The inner dual wheel is held by the "thimble," then the outer wheel is mounted on the thimbles with the cap nut holding it in place. Single wheels just used the outer cap nut on large diameter studs. Wheels are one piece - no split rims here. While this design was a major improvement - it had the problem of additional complexity. As one who has changed many a tire, I can tell you the thimble is the weak point of this design - they often shear the square head end off during removal. This leaves a stub with no way of attaching an air gun or much of any power tool. It was tightened by a big air gun, but it took sweat and blood to get it off. Usually, heating it with a torch and using a pipe wrench and cheater pipe were required. Cursing seemed to help as well.

This is the "metric" fastener. The wheels are now stud piloted, which means the stud holes and the studs match very closely. Both wheels on a dual setup use a common stud, and the single nut/rotating washer assembly clamp the whole thing down. Front axles don't require different studs with this system, and there are less parts to break. It's turned out to be a pretty foolproof setup.

One more thing comes to mind when considering "modern" improvements - the brake slack adjusters. Air brakes, just like any other brakes, require adjustment. Automotive drum brakes have a hidden "star" adjuster that tightens the clearance. Air brakes are external - the adjuster is attached to the rod coming from the air brake pod. The old manual adjusters were pretty foolproof - but you had to climb under the truck with a 9/16" wrench and adjust the brakes at least once a week. If you didn't, you would eventually effectively have no brakes at all. Back in the day, there were automatic adjusters, but they were pretty much failures. Now they work great. I don't have to wrestle my fat ass under the truck once a week these days, which suits me fine. I have to go under when the oil is changed to grease the u-joints and other various moving parts, so if a brake is out of whack with plenty of lining - replace the defective slack adjuster.

Power steering is another arena of improvement. Lots of trucks even into the nineties had Power Steering by Armstrong. Most of the time they weren't that bad - as long as you were moving. Corners had to be thought out a bit better - it took a lot of winding on a manual steering truck to drastically alter it's course. Lock to lock and all. One truck I drove back in the day had air assist. Which meant if I wasn't conservative with my steering while backing, I'd run the truck out of air.

These are the main areas I think of as improvements in technology, where I don't feel that going retro is a good idea. Most improvements are incremental, but one day ya kinda look around and things have really changed. As far as this tubby trucker is concerned, it's for the better.

And just as an aside - it's a lot easier for women to drive a truck these days. I mean that in the physical sense - you don't have to be a strong man to horse a rig around any more. Putting up with truck stop cretins that think they're God's gift to women, and other such misogynistic assholes are another issue entirely. In my mind, that is the area of most concern for a woman considering a trucking career. Actually handling the equipment is not much of a problem any more. If a fat old bastard with no grip and no endurance can do it, no reason why a woman should have any doubts.


CGHill said...

Old Chrysler cars used to have torsion bars up front. I think about that, and I think about the garage-door springs that run on that principle, and I scream.

And now that I look at that suspension stuff, it occurs to me that Dodge is getting all kinds of kudos for getting away from leaves on the '09 Ram pickup. Geez, it wasn't that long ago that Jeeps had leaves on the front.

Anonymous said...

My first pickup, 1962 Chevrolet half-ton, had torsion-bar front suspension.
BTW, good friend of mine works for Ridewell.

Donna B. said...

I've been a passenger in trucks since I was a toddler. My Dad made lots of relatively short hauls from or to his sawmill and one of us kids always wanted to go with him.

My Dad's a talker and a natural-born teacher. He described everything he did and why. As I got older, the trips became general driving lessons... "See that green car up there? Can you tell me what he's about to do? How many and what kind of cars/trucks are behind us?"

What he taught me can be boiled down to three things: know your abilities, know your equipment, and pay attention to your surroundings.

I was 13 the first time he let me drive on the highway, pulling a load of lumber. That would have been 1965 in Colorado, though no mountain passes were involved in that short trip.

Of course, I turned real stupid shortly after that and didn't listen much to my father for the next way-too-many years. But at least I knew how to drive.

Jeffro said...

Heh - it's amazing how our parents lost their knowledge as we grew up, but after we got there, suddenly they started getting a lot, lot smarter!

Jonathan Carol said...

This is very informative! And I agree; trucking technology has been improving over the past years, engine and design-wise. Compared to the older tech, it’s quite easier to use. But without a thorough understanding about it, you might be hard-pressed when it comes to repairing and maintaining even the later models. Thanks for sharing!

Jonathan Carol @ Utility Fleet

Unknown said...

Great write up, but you've got the hub piloted and stud piloted wheels mixed up. Budd wheels are stud piloted, and the "metric style" are hub piloted.