I think I need a bridge truck and have some questions. I have reviewed several manuals and have found bits of conflicting and/or missing information on the bridge trucks. I know several members have them and I was hoping for some help.
(All questions are related to M809 series bridge trucks).
1. There seems to be 2 different models, the M812 and the M821. One has the hyrdaulic A-frame bed (M812) and one has a cargo type bed (M821). Why is the operation of the M821 covered in the M809 series operator manuals but not the M812? The 1977 edition lists a M812A1 as a Rocket Launcher Chassis, and the 1985 edition lists the M812A1 in the dimension and weight tables but does not show what the truck is. Neither manual shows the M812 bridge truck. Why?
2. I did find TM 5-5420-209-12 on the site here which covers the operation of the bridge sections, cargo pallet and transporters (M812 and M945). It shows the ground clearance as 14.5". The M809 manuals shows the ground clearance of the M812A1 and the M821 as 13.1" (vs. 10.5" on a standard 5 ton). Any thoughts on the difference between 13.1" and 14.5"? All 3 have the same tires (14.00x20) and should have the same ground clearance.
3. I have seen different weights and payload capacities for the M812, M812A1 and the M821. Weights are 27,400, 21,501, and 28,880, respectively. Cross country payloads are 12,000, 16,000, and 10,000, respectively. Calculated gross weight would be similar across all three. Highway payloads are up to 26,000 for the M812A1. Can someone with a M812 confirm the weights on their data plate?
4. Why do some M812s have the flat steel grill and some have the rounded? I assume the tubular grills were used after the flat steel grills, but I was told the opposite. Any ideas?
More questions to follow, but I thought this should be enough to get me started.
The Following User Says Thank You to M1075 For This Useful Post:
The tubular grille was prone to rust through, and was replaced with the "strip" grille. All my manuals are still packed from moving - BUT I suspect that these trucks have fallen into the same pit as their predecessors. Many folks will say thay have M139 bridge trucks - they don't - they have M328 bridge trucks. A M139 is a chassis truck - that chassis with the bridge bed on it is a M328. Similarly, I believe the M812 is a chassis (by the way, variants of the M139 chassis - and the M812 chassis - were used for the Honest John rocket launcher).
Not the answers you were looking for - but perhaps clues for you to dig further. If no luck, holler again in a few days, I have many, many boxes of books to unpack.
I'am looking at TM 9-2320-211-10 Operator's Manual dated March 1963 pg 14 sub sec. h. Chassis Truck, M139 the 5 -ton ,6x6 chassis truck M139 has 215- inch wheelbase 14:00 x 20 tires and dual rear wheels.This chassis is designed specifically for transporting bridge building equipment. I know my truck is not the model you were looking for . The book I have does not say anything about a M328. Does state about M139C and M139D designed for transporting the 7.62 mm rocket launcher and have axle gear ratio of 10.26:1 for increased tractive effort. Also a M139F this modified version of the Model M139 is designed specifically for transporting the 386-mm rocket launcher and has an axle ratio of 6.443: 1 . OSO
I'm going to agree with David Dolye about the 812's, from what I've heard or read, the 812 was a 5 ton chassis w/ the A-frame bridge bed on it. the 821 was designed specially as a bridge truck, i think, i remember someone a while ago telling me that. as for the different clearences w/ the same size tires, i have no idea why one sits higher than the other. and about the 2 different stryle grilles the square looks better. just my 0.02USD
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SPC Harbold, Jason
FT. Stewart, Ga. 91B10-HET mechanic
1970 M35A2-my other truck
2004 Chevy K2500HD 6.6L Duramax-my truck
AH1955's son
.... (by the way, variants of the M139 chassis - and the M812 chassis - were used for the Honest John rocket launcher)....
David mentions the Honest John, this image may not answer any direct questions, but may be a lead. The launcher was tagged M289.
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Bjorn
MEP-018A (needs new generator head)
Avatar: XM757 in OK prepared for 1,000 mile trip home. Part of 6,000 mile journey in 2006.
1968 M49A2C modified with 1960 M756A2 truck bed and 1975 HIAB 765A knuckleboom, exhaust brake, VIC-1 and more.
1969 Ford XM757 8x8, 5-ton Pershing 1A truck tractor...the "improved MV".
"Some things can't be made better, just differently......a lot of things actually"
Yep, that is the M289, the earlier one - the later one with the short launch rail is a M386. Got a few boxes unpacked last night. The TM for the bridge stake bed is TM 5-2510-200-25P - no help there, just trivia.
As pointed out earlier - the M-number of the chassis is easy to find - most of the TMs list it - finding the M-number of the complete truck (when one exists) is harder to find.
Uh oh. I've heard this before, and it doesn't look good for your future, or for your wife's plans of getting expensive jewerly for Christmas either. Someone has the OD bug!
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Mike
maddawg308
FCC # W1AMR Extra Class
MVPA #33431
NRA Life member
2003 Dodge Durango SLT 4.7L V-8 parts hauler
1967 Stevens M416 trailer
owner of the "Dawg House" travelling Vietnam radio hooch display
avatar: Capt. Malcolm Reynolds from Firefly/Serenity
Several Bridge Truck Questions
OSO
