T-Mack1

There are a bunch of different types of challenge coins. Which ones are you talking about? The "You Make a Difference" coins that originally went out to empolyees?

I'm taking a rain check. Although, I think my brother Jack will be there. I'm pretty sure our B85F will not be ready this year. I'll be at the Mini-bike reunion in Windber, Pa. I've been going there for 20+ years. And yes, I know Macungie is walking distance from my house, but the reunion is at "Restoration Specialties", the window and door seal place, so I may be scouting out some parts for the truck.

Does this include our 3-Phase Leece-Neville Alternator with external rectifier & regulator? All the terminals are isolated from the case to include the two going to the rotor that, according to the service manual, only has 2 wires. My understanding is that the rectifier would fry as you would be connecting the Neg wires to the cathode paths of the diodes making a "short".

A lot of interesting things here. Here's my few bits of wisdom I've learned. -Not all alternators will be damaged when reversing polarity. Only ones with build in rectifiers (diodes). Alternators with external rectifiers like the Leece Neville system on our '57 firetruck (B85F) should be ok. BUT, the rectifier will have to have the output wires switched (big sparks otherwise). If it is a "case grounded" rectifier, identified by only having one output wire, you would have to isolate the case to switch polarity. Our original Selenium rectifier and the new solid state one we now have, have isolated Pos & Neg outputs, so one output wire goes to ground. - Electric motors without permanent magnets use how the windings connect to the brushes and commutator that they rub against, to create the magnetic field to "pull" the rotor (spinning part) around. It uses the "Opposite poles attract" theory as a pull (or the "Like" poles repel as a push). So, it doesn't matter if the "Positive is pulling a Negative", or if the opposite happens and a "Negative pulls a Positive" . It is still pulling in a direction set by the windings. - Many older (non-solid state) voltage regulators work basically on a voltage "threshold" principle, where it looks at voltage level, not voltage polarity. There are theories to explain it, but simply, If the voltage is too low it sends more voltage to the field to create a higher output voltage. Once it get to the desired voltage ( the threshold) it holds the field steady. If the voltage goes past the threshold voltage it reduces the field down a little. All this is done at almost the speed of light.

Ok guys, while volunteering at the Mack Truck Historical Museum, I had chance to work on a steering column mounted Signal Stat turn signal module with the rare 11 wires. Since the internet doesn't show the wiring for them and the unit is obsolete, here is the wiring explained. Signal Stat (Sigflare) 900, 11 wire Standard wires (also on the on 6 & 7 wire units): Blue (if present) - Input for internal indicator light (from 3 prong style flasher module, "I" pin) Yellow - Input from flasher module (blinking on-off) Gray w/Black trace - Input from Brake switch Green - to Left front turn signal light Red - To Right front turn signal light Gray - to Left rear Turn/Brake light Black - To Right rear turn/brake light The 4 wires extra wires Red w/Black trace - feeds power to front turn lights filaments when turn lever/4-Way is not active (NC). Opens appropriate contact when lever actuated and connects it to flasher, and the other light stay as marker/parking light. (use ballast resistor to dim filaments for running/parking lights) White - Auxiliary Common (NC) White w/red trace - Auxiliary Right White w/green trace - Auxiliary Left Notes: 1) Aux connections are "Normally Closed" (3 white leads tied together). Lever actuation "opens" the appropriate wire/connection). (( I have no clue how this would be used.)) 2) If you have the blue wire, you need to use the correct flasher module that has the indicator output pin 3) Warning: on most Signal-Stat steering column mounted units, using the 4-way flasher slide bar, disconnects the brake lights. Keep that in mind if driving with someone following too closely. enjoy, Tom M. diagram

That's Bob Nuss, The owner of Nuss Trucks (Mack, Volvo dealership with multiple locations) and also the museum.

The two things are called circuit breakers, and are available at most auto parts stores. Also on Amazon. Normal ratings are 10A, 20A, 30A and 40A. Some come as 6v and some 12v. You can get some other amp ratings but might be harder to find. They are also called thermal circuit breakers as they reset when they cool down. They can go bad. Arching as they open up can eat away at the contacts. Also, as said above, those corroded wires will cause an extra load on the circuit too. Hopefully the corrosion doesn't go too far back into the wires, so that you can trim them shorter and add a new connector. Although the one wire looks pretty short already.

I will when I get back down to the truck. It's at my brother house. But, I'm not so sure it would be much help as it's a Firetruck which means a Gasser engine ENF707C (in 1957 they took less time to warm up and get moving). Yes, it's a Thermodyne but that just means it sort of shares some features that a diesel has. Similar block. The Compressor is in the same spot, but in place of the diesel fuel pump, we have ignition distributors (two since it's a firetruck).

Here's a Picture of our compressor "Unloader" (AKA the governor). It is working and has a range, where it turns off the compressor at 120 psig, and restarts it around 85 psig. Note: before starting the truck we sprayed some PB-Blaster in all the ports.

Attached picture is when we converted to Spring brakes. Left side is new dual chamber spring brakes, right side has the single chamber "service only" chamber. Conversion requires a quick release valve (QRV) and a park brake valve (& knob on dash), plus plumbing work. We used plastic pipe (synflex). Next, the way the forum is setup, you only get so many bytes of upload for free. I spend the $75 to get unlimited upload. Makes showing/helping others easier. It also helps if you are asking for help and want to show a picture.

Nice find. Your compressor unloader (also called a governor) looks like the one that is on our '57. It's the thing on the right side of first picture (horizontal cylinder). We don't have an air dryer (wet tank only), so ours only has 2 lines. Bigger line from air tanks, and 1/4" line down to compressor to "unload"/turn off it off when pressure is reached. If you need a picture, let me know. I'm not sure what the other two things are in the picture. We have a low pressure alarm switch in that area but it looks different. Next, I see you have a drive-line parking brake (brake lever in cab). Do you have "service only" on the rear or did someone convert it to Spring brakes? Ours was service only but we converted to spring brakes.

Yep, Mack made boat engines. And stuff for railroads, but that was mostly small tugs.

Glad to hear you got them off. The sweet feeling of success is a great thing!!!!!

Have you tried to apply heat to the engine block to expand the metal? And, heat cycling where you use a penetrating oil to cool it back down may help. DO NOT hammer on it. The metal could be brittle with age.

Online auction is active. https://tomhallauctions.hibid.com/catalog/706752/01-20-2026-mack-truck--primitives--beer-items--plus-