mechohaulic

quick look it seems like 4 wreckers set to retrieve the load. study closer 'it's 3 white wreckers and what looks like a 4th blue wrecker is actually the rear section of trailer. or I really do need new glasses...

don't feel bad about the laugh; i got basically the same reaction going to a john deere dealer and asked for a clutch assy for a 1984 JD 1450 i have apart right now. things are definitely different in today's world . that brake switch should be the same in later yr vehicles also. 1/4 or 3/8th pipe square top with two Philips head screws . unless it's totaled ;take it apart and emery the brass contact plate inside.

glad I'm not the only one with that thought . LOL .

one thing to keep in mind, much like the emergency shut off on the DD's ;; it called emergency for a reason. too many times of use it will suck in the seals on a turbo. engine at over high speed wants air from some where till it starves. a pair of vise grips flatting out the fuel supply line in some cases will be faster than taking off the intake hose to access the intake, NOT saying the flat piece is wrong;; anything to shut down a run away fastest .in total agreement regards to the plunger being the cause.

my number one priority would be to jam a rag in that drain hole to stop metal contamination going further in the oil system.

broken /weak spring in oil pad high pressure over ride, engine won't know it gauge and electronics will

if you are going to replumb this trailer with intent of running the road , law might say it must be done by todays standards meaning has to have spring brake parking brake. in that case clearance can be a situation requiring 24/24 cans . use to need two separate valves (R-8?R-6). modern technology must have a dual system valve set up; that can be effective yet simple for install. i wouldn't be concerned as to what it had but what will you need that will be safe and up to standards. good air tank, combo valve to screw directly in tank, 4 maxi cans or 2 maxi and 2 plain service cans . don't think anyone bothers with hose length vs hose size. should be 1/2 dia hose.

the old style trailer brake systems did NOT have maxi ( mechanical spring ) brakes . the single diaphragm can acted as a service brake and ALSO a parking brake. the magic was the valve it self. the valve screwed directly into the tank. brake application service side == air was directed through valve to brake cans. when disconnecting from trailer the brake valve closed an internal port and opened another sending air to the cans to hold brakes. imagine some little munchkin in the valve holding his foot on the port to keep air pressure going to cans, when the system lost it's air, "parking brake " was no more; resulting in trailers rolling away when fifth wheel backed under and landing gear came off the ground. that was the reason for the ridiculous procedure of back up to the trailer not touching the fifth wheel to trailer;; get out hook the hoses= charge the air system then apply trailer parking brake == then back under. even after the maxi can spring brake can was mandatory ; D O T inspectors made you follow the rule of the '40's/50'swhen going for CDL test.

thanks right back to you for the latest update.it does become frustrating when questions are answered by many on this forum and the "questioner" just vanishes from the planet, LOL .

do you have an air dryer that hasn't had the filter changed restricting air flow ??? being a '70 doesn't mean someone hasn't "modified" things through the yrs . has this issue been there or just become noticeable ??

when you say " all 4 segments drop the same" , does this unit have dual air system ( red and green needle on gauge);i don't remember when that started. when dump body was installed, were the air tanks moved or replaced? the main wet tank has a check valve connecting other half of tank;; when gauges are at 130 if you open each drain on the tanks individually ; does each drain have full pressure of air coming out ? have seen the one way check limit air to other tank half. tank not having an external check has one internal , pain in a-- to change, AFTER draining tank remove fitting on end of tank flashlight can see the internal check, long extention and grease on the socket will remove the check. have also seen an improper discharge line from compressor become restricted from wrong line too close to high heat compressor air. also as you stated ;;yes older units weren't made to build air like todays iron ;; NOT counting fire apparatus ; they had a rapid build up system.

what are you running for a signal light switch? old square original box or has it been updated ?

how many wires running to the back tail lights ?? rear turn signals on tractors didn't come to be till later yrs. were they working= now don't ?? brake switch is air operated .. front signals working ?? B61 tractor or straight truck.if it's tractor, are brake lights working in light plug ?

So when the Mack museum calls and makes You an amazing offer ; will you be able to say -yes or no. with out a doubt all Your effort has paid off and You have built an above museum quaility show piece.

depending on how the term "longest serving " title is meant, i know the R -model fire truck i delivered while working at waterbury mack in CT to winchester center back in '71 is still there may only be for parades or major emergencies . CT has (had) a ruling a fire apparatus can only remain front line equipt for 20 yrs. many times after the 20 yrs a unit is sold/ donated to another dept.

you didn't circle the difference of the one dot vs two dot in the trees under the big red circle of the trees and the air intake difference circled in red.

sounds like my marriage==first look -not bad; start pokin , moving "stuff "around ;; then the issues start add😁ing up 🤣, once again couldn't help myself LOL

once again it's proven never too old to learn. after 50 + yrs of wrench pushing, wasn't aware the first digit in the B series indicated weight rating.. sure makes sense . B 81 == 80 k weight with diesel. thanks for info..

I had an extensive set of left -hand drill bits just for that reason. lucked out many times when the left hand drill bit screwed the broken bolt out.

when men were men LOL. didn't need 600 hp or auto trans . didn't haul as many loads either ;; hey can't have everything

welding on the flange would ultimately crack the flange. many of the u-bolt set ups had flat stock welded to the 5th wheel and ran along top of frame having other end welded to rear of frame rail location of less stress . another thought, when days of u-bolt mounting took place, trucks weren't (on a regular basis) carrying 100 K payloads. still find myself totally amazed looking at old pictures of loadbeds hauling huge construction equipment using chain drive tractors. air brakes ???😄 no. had friend tell me of him loading old cable excavator on flat bed ; when he started up rear of trailer the tractor lifted off the ground and away the whole unit went, tractor was the only source of brakes (hand brake)..LOL

back in the day; 5th wheels were mounted with only long u-bolts ; way too much movement. most all wheels mounted later were bolted to their own plates which were bolted to angle iron bolted through the frame rails not the frame flange . as stated earlier, with out the main frame plate on the 5th wheel too much flex would be on the chassis. of the 50-60 + 5th wheels i mounted while at Mack none were direct mount to the frame. all were either welded to angle iron bolted to the frame (sliders) or bolted to the iron that was bolted to frame (fixed).

sure hope this forum receives follow up on this truck not only fixing the run situation but a few facts (engine, trans etc ) and updated pictures . R 700 is a nice ride to have .

just a thought if the truck is sitting in the field (high grass) i would take a clean 5 gallon can of fuel = hook in to the supply line ; possibly remove primary (red) fuel filter to check for contaminated (water etc ).proper way replace filter with new clean fuel not that bad drain it and fill it and reinstall ;;; only to get the truck in a more suitable location for repairs. only going by the picture shown.then follow ALL the ideas above.

today's law enforcement vehicles are titled " robo cop cars. I can remember the ford galaxies. I was a caretaker for a few homes in town even then they were broken into, so i used what was called a house phone (sorry youngsters ). point is watching the fords pull in the driveways. beside the car when the door opened out steps this Trooper at least 6ft tall or more( there were height restriction then) and proceeded to put on this tall hat making him look 7 ft tall. remember when the large single blue strobe lights were installed! that was technology back then