US Gear Surprise

Robt.Webster · Sep 23, 2015

My US Gear overdrive recently stopped shifting and is stuck in direct mode. After reading the many posts about this drive, I purchased a replacement set of switches and a shifting motor. I pulled the side plate today expecting to find a bad set of switches, only to find no switches at all. The motor leads were wired direct to the external terminals, although everything required to install and use the switches is there.

The box has been working with no problems. I am the original owner of tbe truck and had the overdrive installed by a reputable shop back in 1993. The truck is the one shown in my signature.

Has anyone seen this before? I have heard that US Gear sold some models that used current sensing in control boxes to stop the motor travel; is this one of them?

Since these control boxes are as rare as hen's teeth these days, I am thinking it might be better to install the switches and allow them to stop the motor travel. Would be a much simpler control scheme and may be more reliable in the long run.

Any thoughts on this?

Thanks for any feedback.

OLDBULL8 · Sep 23, 2015

Did you run into this on your searches.

http://www.oilburners.net/forums/showthread.php?65234-US-Gear-Dual-Range-Doug-Nash-Info

Robt.Webster · Sep 23, 2015

Old Bull, I looked at it previously, but went back and looked again. I did see the mention about the difference in control systems between the US Gear and the DNE units. What confused the situation is that my box does not have the position indication switches mentioned, and the manual that came with the box shows the motor cut-off switches under the cover and references them in thé repair instructions.

Perhaps this is an early box that carries features from both designs?

Found one of the motor leads with the conductor broken off in the wire jacket. Will have to see if can be repaired without pulling the box. Would be the short one, naturally.

As long as the cover is off, I need to decide whether or not to install the switches and wire the center pole of the in-cab shift switch to an ignition switched source and abandon the US Gear control box.

Any thoughts?

Appreciate your feedback.

OLDBULL8 · Sep 23, 2015

I've got a US Gear, it's stuck in OD and the electronics don't work, and one position switch is gone. Don't plan on working on it. Suits the hell outa me with double OD. Can't help ya any.

Robt.Webster · Sep 23, 2015

. Understand your point. I tow a 12,000 pound 5th wheel at times, and the direct mode is appreciated tben even with the 4.10 rear end. At all other times, the OD engaged would be the rule. Much better fuel milage, and first gear actually serves a purpose LOL

.

There are nice little solid-state single-shot relays out there that can provide a 2 second pulse outputupon energization at a reasonable price. May look into making my own control unit since it seems that these switches are failure prone and a real PITA to change without pulling the box.

If you are interested, I will let you know how I make out.

Robert

Black dawg · Sep 23, 2015

You have power and ground to the box? I have found the connector at the box isnt very positive.

If you have the stuff to wire it up with the internal switches, I would do that, as the boxes are pretty tough/impossible to find. The control box seems like alot of extra stuff to do what the earlier ones did without it.

Robt.Webster · Sep 23, 2015

Í do have a brand new set of switches in hand, and the box has all of the facilities to install them.

Would be the quickest fix, but if the switches are as problematic as seem people indicate, may be back in there sooner than I would like.

I loved the box when it worked, and would like to get it functioning again.

wwwabbit · Sep 24, 2015

If you found a broken wire, why not just repair the wire and see if it works? I would not see the need to change anything else if the broken wire is the problem.

The Warden · Sep 24, 2015

Robt.Webster said:
There are nice little solid-state single-shot relays out there that can provide a 2 second pulse outputupon energization at a reasonable price. May look into making my own control unit since it seems that these switches are failure prone and a real PITA to change without pulling the box.

If you are interested, I will let you know how I make out.

If you end up doing this, PLEASE post results! As someone who has a late-model U.S. Gear overdrive unit without any of the electronics, I'm VERY interested in what you come up with ;Sweet

junk · Sep 24, 2015

Give Rose Auto Clinic a call in California. http://roseautoclinic.com/

He has new electronics for US gears still. I believe they are even for the newer units. Guy is super nice. I called him when I had troubles with my unit. Mine ended up being a stuck motor. Been fine after freeing it.

Good luck the US gear are a nice unit.

-Jeremy

jaluhn83 · Sep 30, 2015

To the best of my knowledge, there is *no* fancy current sensing system, it's a simple timer. The lead screw design is overrunning, so once it reaches the stops (roll pins through screw at each end), the screw simply spins. Likely not good to let it run for too long this way, but 1-2 seconds doesn't hurt anything and there's no fancy electronics required.

Try putting 12 volts to each of the terminals on the side of the box (the ones that would go to a switch on the DNE unit) and see what happens. The motor should run and you will hear the mechanism move and then stop with the screw freewheeling. Each terminal goes one way, so by alternating which one you put 12 volts to you should be able to shift it back and forth. I don't recall which terminal is which gear, but even if it's already in gear you should still hear the motor run when you connect it. If the motor works both ways then the problem is either wiring or the control box. It may be that one side of the motor is bad, which you will see by it not running that direction.

If it is the control box, I would just stick the limit switch unit in there and wire it directly to a toggle or push/pull switch. Chances are good that it would just be a bad relay, and hence the box could be fixed, but it wouldn't be that easy. If this does prove to be the case, I would like the box to attempt to fix/reverse engineer it. If you stick the new switch in make sure that the plastic bushings on the terminals going through the case are there, and IIRC there is an o0ring on the outside to seal it.

To make sure we're on the same page, the 'set of switches' you're looking at is the internal switch unit that has a plastic back and 2 terminals, right? Wanted to make sure you're not looking at the 2 small screw in switches further back on the box since these have nothing to do with shifting.

Robt.Webster · Oct 2, 2015

jaluhn83 said:
To the best of my knowledge, there is *no* fancy current sensing system, it's a simple timer. The lead screw design is overrunning, so once it reaches the stops (roll pins through screw at each end), the screw simply spins. Likely not good to let it run for too long this way, but 1-2 seconds doesn't hurt anything and there's no fancy electronics required.

Try putting 12 volts to each of the terminals on the side of the box (the ones that would go to a switch on the DNE unit) and see what happens. The motor should run and you will hear the mechanism move and then stop with the screw freewheeling. Each terminal goes one way, so by alternating which one you put 12 volts to you should be able to shift it back and forth. I don't recall which terminal is which gear, but even if it's already in gear you should still hear the motor run when you connect it. If the motor works both ways then the problem is either wiring or the control box. It may be that one side of the motor is bad, which you will see by it not running that direction.

If it is the control box, I would just stick the limit switch unit in there and wire it directly to a toggle or push/pull switch. Chances are good that it would just be a bad relay, and hence the box could be fixed, but it wouldn't be that easy. If this does prove to be the case, I would like the box to attempt to fix/reverse engineer it. If you stick the new switch in make sure that the plastic bushings on the terminals going through the case are there, and IIRC there is an o0ring on the outside to seal it.

To make sure we're on the same page, the 'set of switches' you're looking at is the internal switch unit that has a plastic back and 2 terminals, right? Wanted to make sure you're not looking at the 2 small screw in switches further back on the box since these have nothing to do with shifting.

Thanks for the information. The current sensing module seemed a bit much, as I understand that the screw gear has end-of-screw run on protection, so the motor current would never increase by much at end of travel.

I have been in touch with a manufacturer of solid state relays that indicated that they might have a new relay coming out soon that would two inputs/outputs with TDO and pulse output capabilities. This would essentially duplicate the US Gear controller function. The TDO feature would be nice in that the time delay on could be set in a way to eliminate accidental range changes.

If this doesn't work out, then I will install the internal switches, but would rather pursue the first option as any failures there could be resolved without opening the box.

It's been raining here quite a bit and the ground is saturated, so since I am working outside I am going to wait a bit. As soon as things dry out a bit, I will be testing the shift motor in the manner that you mentioned.

This seems to be a bit of an odd animal for a US Gear unit from what I have heard. It does not have the position switches on the rear of the unit that you mentioned, nor does it have the internal switcdhes. Odd thing is that the motor wiring is internal, not external as some people have indicated is the normal case for US Gear units.

jaluhn83 · Oct 2, 2015

Please post pictures if you can.

What do mean by TDO (I assume that's "time delay output") eliminating accidental range changes?

All you need is a system that will put out a ~1 second 12+ output when given and input signal, either constant on from a push/pull type switch or a momentary from a momentary switch. Did some searching and it looks like trade term for this is a 'one shot' relay and these are easy and fairly cheap.

http://cdselectronics.com/kits/timer%20relay.htm
http://voconversionbasics.forumchitchat.com/post/simple-12v-timers-3490145

Use a switch, 2 of these type relays and some simple wiring and you're good. If you want to be safe use the one shot relays to drive a standard auto cube relay, though I doubt the shift motor draws more than a couple amps.

junk · Oct 2, 2015

I believe the older US gear units used a standard Eaton style motor. like this. The wires came out into the lead screw housing. And on this housing is where some eaton switches would mount.

On my setup the motor wires come out the back of the motor and then go to the control box. According to Rose Auto Clinic I have one of the "newer" styles.

I completely agree it sends voltage for like 1.6 seconds then reverses polarity on the next switch pull.

Robt.Webster · Oct 2, 2015

jaluhn83 said:
Please post pictures if you can.

What do mean by TDO (I assume that's "time delay output") eliminating accidental range changes?

All you need is a system that will put out a ~1 second 12+ output when given and input signal, either constant on from a push/pull type switch or a momentary from a momentary switch. Did some searching and it looks like trade term for this is a 'one shot' relay and these are easy and fairly cheap.

http://cdselectronics.com/kits/timer%20relay.htm
http://voconversionbasics.forumchitchat.com/post/simple-12v-timers-3490145

Use a switch, 2 of these type relays and some simple wiring and you're good. If you want to be safe use the one shot relays to drive a standard auto cube relay, though I doubt the shift motor draws more than a couple amps.

Sorry, meant "TDP" for time delay pickup for a relay where the output is delayed upon receiving an input.

A 'one shot' relay is also known as a 'single shot' or a pulse.

A relay that would suit this purpose would be the TRD-M from Wolsten Tech (http://www.wolstentech.com/products/timedelayrelay/tdr-m.php). I have used these relays for several other projects before and have been extremely pleased with them. These solid state relays are capable of 10 amps continuous and come in a compact form factor. It would take two of these unless they come out with the new relay that combines two relays into one first.

The on delay could be set to one second or so to prevent accidental triggering (my switch is on the gear shift and have accidentally triggered it before), with a 2 second pulse output for driving the shift motor when a range change is desired. Might take an additional relay to prevent triggering both motor inputs simultaneously, but could all fit in a small electronics box similar to the US Gear control module. Power to the center pole on the range selection switch would come from a switch ignition source to prevent driving the motor if the key is off and the range selection switch is actuated.

US Gear Surprise

Robt.Webster

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OLDBULL8

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