Chain Drive

[41chevy]

41Chevy. Thanks for the brochure pics, they definitely made a lot of improvements over the run. My shifter is primitive compared to the pics you sent, and no vacuum or front brakes. Mine was a crane too - found this old picture of it on line, but the crane was scrapped. I guess you drove slowly and down shifted often - no to mention steering! Sorry, look closely it was behind a spring shop for years.

image.jpg

MACK made running improvements as the were developed the put them in to production. The shifter in the brochure is a 4 speed in a 5 or 7 ton unit so it is much different. I agree on the quality of the castings and hardware and machine work a lot of pride in it. I hate to say it but in some instances in better than on my B-61. My AC-6 was in use until 1978 or 1979. If the drive to turn the house didn't fail it probably would have been used longer.

I would expect not a lot of down shifting with the straight cut gears and the long linkages. Two of mine have a momentary magneto kill button on the wheel, I almost think it would kill the magneto to give you some engine brake.

NY-B61, my dad and uncle got me into collecting old catalogs, repair manuals and photos. They were into antique trucks and cars when most considered them just used vehicles. Paul

[Jeff M]

Question: The sprocket drive unit would have been a differential type, wouldn't it? Or did they just use a "straight axle" type of setup?

[41chevy]

On the "Tire End" it's a straight axle, the drive sprocket is on the brake drum. The primary drive sprocket is on the trans-axle which has a ring and pinion and spider gears.

Front unit is 3 or 4 speed transmission , rear is differential and stub axles to primary sprocket.

[gearhead204]

was there different drive or driven sprockets to change final wheel speed ?

[b615rich]

I'm no where near the expert 41Chevy is, but people do discuss changing the drive sprockets for a higher top speed (the drive sprockets are easy to get at and sprockets on the wheels are about 24 inches, so no much you can do there). There is a story of a guy who changed sprockets plus some other mods to get highway speeds from a chain drive (a hair raising thought!).. Link below, nice looking truck either way.

http://forums.aths.org/43526/Chain-Drive-Macks

[Gmerrill0516]

If the brakes are working too hard you can just flick the switch on the dash to enable the jake...Works great every time. I'm guessing you paid a good deal of attention to load, road conditions and hills even more so than now...If you didn't you probably didn't live too long even at reduced speeds...Yikes.

[Superdog]

I'm no where near the expert 41Chevy is, but people do discuss changing the drive sprockets for a higher top speed (the drive sprockets are easy to get at and sprockets on the wheels are about 24 inches, so no much you can do there). There is a story of a guy who changed sprockets plus some other mods to get highway speeds from a chain drive (a hair raising thought!).. Link below, nice looking truck either way.

http://forums.aths.org/43526/Chain-Drive-Macks

I borrowed this pic,but it was taken at Walcott the year Art Robinson brought his AC,he was a super nice guy,and really took a liking to Mikey. Art couldn't see very well so didn't get to drive his trucks.didn't stop him from enjoying them,though. I was standing out next to the show entrance talking to some people,and next thing I knew,this AC came flying by,Mikey driving and Art riding.

[Speed]

picture a trip down loveland with those brakes and about 12 tons on the back

Okay--is there a problem with this? Why do ya think they're so LOW geared? (Besides a little less power than is adequate...)

[carlotpilot]

the pic I commented on coupled with 12 tons which is I think more than twice what that little truck was rated for` down hill on loveland pass when the truck was in its day would have equaled your handle +++++

[41chevy]

Change final drive ratio by going up or down on primary drive sprocket. I have a few different ones. The standard is 14 tooth, I have OEM 12 and a 13 tooth primaries that were a $8.10 factory optional pack. Rears are 39 and 43 teeth. I have an after market set from 1937 that are 21 primary and 47 final. With the 40 x 6 rear wheels and tires it would give you a top speed of about 50 + at 1600 RPM.

Loads? This was at the high end of normal Early 7 1/2 tonner with NO front brakes by probably have Bendix Vacuum Assist with a trailer load rated for 60,200 pounds ( 28 long tons) . Truck weight + trailer weight + 95500 pound (44.4 long tons) Marion, all pulled with 70 or 74 h.p. in the BRONX .

[Speed]

Change final drive ratio by going up or down on primary drive sprocket. I have a few different ones. The standard is 14 tooth, I have OEM 12 and a 13 tooth primaries that were a $8.10 factory optional pack. Rears are 39 and 43 teeth. I have an after market set from 1937 that are 21 primary and 47 final. With the 40 x 6 rear wheels and tires it would give you a top speed of about 50 + at 1600 RPM.

Loads? This was at the high end of normal Early 7 1/2 tonner with NO front brakes by probably have Bendix Vacuum Assist. Truck weight + trailer weight + 95550 Marion, all pulled with 70 or 74 h.p. in the BRONX

ac plus.JPG

Reminds me of re-gearing my old Harley. (the '80-80) Changed the transmission output sprocket on it from a 22T to a 24T and the wheel sprocket from a 51T to a 46T. After that,it'd roll down the road at 75 turning a leisurely 2300 revs.( I COULD have gone further with it by changing the motor sprocket from a 22T to a 25T,but that would've been overkill.) That kicked my mileage past the 50 mpg mark by a ways too.

[41chevy]

Got to remember one thing with all the teens and twenties trucks and the brakes, gearing and power. In their day we had may 20% paved highways with macadam or concrete. Most were still wagon trails or less. City roads were cobble stone or packed dirt and clay either oiled or watered. A lot of places these trucks went our modern units would have a ton of trouble with. As for the loads, those people never knew it couldn't be done most times they were the first motorized vehicles to move the loads and go where they did. Early drivers were real teamsters who went with the trucks the same places they went with the horses or mules.

AC MACK could be gotten with an optional 7 and 2 gearbox. I don't know anybody who ever saw one except in the spec sheets.

My grand mother would drive into the corn field with her Packard and most times get stuck. Could never understand why when she had a horse and buggy before the Packard, she wouldn't get stuck. Paul

[NY-B61]

The history lessons, and pictures, are appreciated as always. Interesting to see what people were able to accomplish when there was nobody there to tell them "It can't be done." The picture of the 7.5 tonner is amazing. Wish I'd been there!

[Superdog]

one thing about it,they didn't have to worry about blowing out any tires.

[NY-B61]

one thing about it,they didn't have to worry about blowing out any tires.

[b615rich]

That shovel on the trailer probably beats all the logging trucks and Hoover Sam trucks I've seen in pictures!! Imagine being the one to say "hey, I've got an idea... Let's pull a shovel with it.." These guys were real innovators.