KTM Motor Rated Voltage

Well, I suspect it's rated at more than 6V, so that makes sense.  What is the make/model of engine?  I'd suspect it's at least a 12V rated motor and more likely 15V or 18V.

It is a PSC factory painted Crown Niagara. I thought of operating at 15-16 VDC, but I know from experience that the brush life of can motors is shortened above rated voltage. It runs at 42 smph at 12 VDC at the track, at about 1.7 amps. Too slow for passenger service.....

A lot of the brass locomotives were geared pretty high, some of the Williams brass was 44:1 and had a top speed of around 40 scale MPH.  If this is a stock 2-rail O-scale locomotive, it has to have at least a 12V rated motor.  If it's running light, I'd think 1.7 amps is a bit much for current consumption, I can see why you're concerned.

I don’t know what the KTM can motor’s voltage is, and not 100% sure what PSC spec’ed for their model built by KTM, …..the UShobbies Niagara is around 20:1, so getting some higher speeds shouldn’t be an issue if PSC used off the shelf KTM engineering. If you’re looking to make this engine better, first thing is to ensure a smooth, easy rolling chassis with the gear box and motor disconnected for the moment. With the gear box & motor disconnected, you can roll the chassis noting & adjusting any binding, etc, ……Once that’s sorted out, then determine the actual gear ratio for confirmation, and then we can all help you pick the best motor for the job. I agree with John, if you’re running the locomotive light, ie; no cars, and you’re drawing 1.7 amps, that seems a bit excessive,…..a load is going to make that skyrocket. I’ve repowered quite a few KTM’s, but not that particular PSC version. How much much weight is in the boiler can also be a factor, especially if it weighs as much as a Pontiac,….I’ve had my Niagara’s up at 60 SMPH, & I can tell you, that’s rolling,….enough to make your backside pucker…..So, the steps I would take would be to first ensure the engine rolls as smoothly, and bind free as possible, with the gear box disconnected to remove the variable, then determine the actual gear ratio as per that particular model…….KTM’s stock, are not known for the ridiculously crazy gear ratios Weavers & Williams are known for ……

Pat

Hello Harmon,

I am pretty sure it is the motor. I disassembled the engine as it appeared to never have been run. With the gearbox removed, mechanism is very smooth and free rolling. I lubed the wheel back faces, the axles, the pedestal guides, and the rods and valve gear. I disassembled the gearbox, cleaned out the old yellow grease, lubed and reinstalled it. I could easily turn the gearbox shaft after assembly. The boiler weight is the same as my other Crown Niagara. I did not count the final gear ratio but I have a Crown Niagara I bought new in 8/1982 and it had a single cut worm, a combo gear with 16/20 teeth, and a final drive ration of 25:1, so I think my new engine is the same.  Many years ago I installed a double cut worm and a 9534 Pittman (5980 rpm) in my older Crown engine. I operate it and my other engines at no more than 9-10 volts. I can advise that these Crown Niagaras do not like a 60-inch radius curve layout, and are very stiff compared with the older USH Niagaras. (I have a USH I remotored with a 9534 Pittman and at 12 VDC it runs at a scale 61.3 mph. The USH engine will readily transverse a 60-inch radius curve and would most likely negotiate something with a sharper radius.)

With the mechanism reassembled, I placed my thumb and index finger on the motor and the gearbox, and there is no detectable vibration. The stabilizing bearing between the motor and gearbox has no bind, and that was lubed as well. I ran the assembled engine at exactly 12 VDC at the rail and it runs at 44.2 smph warm after about 20 laps and about 1/2 hour of operation. I used the ammeter in my Bridgewerks power supply and it appears to operate at about 1.7 amps. I also ran the engine at 12 volts with 26 freight cars and amperage was about 1.8 amps. (These meters are small and the Bridgewerks designer admitted that both voltage and amperage are not calibrated, but should be used as "indicators".) I used a separate meter to measure actual track voltage.

So it looks like my choices are to either operate the motor in excess of 12 volts or install a double threaded worm. I know that a 15-20% overvoltage on an open frame USH motor will throw a winding...not sure about can motors.

I posted on my remotor thread that I checked the speed of a new KTM 4462S at 12V no load and it was 6000-6500 RPM.  Speed seems to match Hudson6542's Pittman9534.

@Hudson5432 posted:

Hello Harmon,

I am pretty sure it is the motor. I disassembled the engine as it appeared to never have been run. With the gearbox removed, mechanism is very smooth and free rolling. I lubed the wheel back faces, the axles, the pedestal guides, and the rods and valve gear. I disassembled the gearbox, cleaned out the old yellow grease, lubed and reinstalled it. I could easily turn the gearbox shaft after assembly. The boiler weight is the same as my other Crown Niagara. I did not count the final gear ratio but I have a Crown Niagara I bought new in 8/1982 and it had a single cut worm, a combo gear with 16/20 teeth, and a final drive ration of 25:1, so I think my new engine is the same.  Many years ago I installed a double cut worm and a 9534 Pittman (5980 rpm) in my older Crown engine. I operate it and my other engines at no more than 9-10 volts. I can advise that these Crown Niagaras do not like a 60-inch radius curve layout, and are very stiff compared with the older USH Niagaras. (I have a USH I remotored with a 9534 Pittman and at 12 VDC it runs at a scale 61.3 mph. The USH engine will readily transverse a 60-inch radius curve and would most likely negotiate something with a sharper radius.)

With the mechanism reassembled, I placed my thumb and index finger on the motor and the gearbox, and there is no detectable vibration. The stabilizing bearing between the motor and gearbox has no bind, and that was lubed as well. I ran the assembled engine at exactly 12 VDC at the rail and it runs at 44.2 smph warm after about 20 laps and about 1/2 hour of operation. I used the ammeter in my Bridgewerks power supply and it appears to operate at about 1.7 amps. I also ran the engine at 12 volts with 26 freight cars and amperage was about 1.8 amps. (These meters are small and the Bridgewerks designer admitted that both voltage and amperage are not calibrated, but should be used as "indicators".) I used a separate meter to measure actual track voltage.

So it looks like my choices are to either operate the motor in excess of 12 volts or install a double threaded worm. I know that a 15-20% overvoltage on an open frame USH motor will throw a winding...not sure about can motors.

I agree with the open frame motors you’d toss a winding, ……..Something doesn’t add up with this engine. At 12V that locomotive should be screaming!…..42 SMPH is awfully slow at 12V, …..most of my junk is between 18-25:1 and I can easily hit 100 SMPH with Pittman power either 12V or 15V …..usually around 13-14V applied, …right around an amp or an amp & a half,……So either that one has an oddball gear ratio, or that KTM motor is giving up the ghost??…..Gray said he saw 6000 rpm on a KTM motor??……that’s right in line with most Pittmans …..most Pittmans surrender around the 6K mark anyways ……

Pat

Is there a chance that this RH-4462S is a 15 or 18 volt? I can't find a rating for these on the web, and the case of the motor has no ratings/markings.   The engine does run at a scale 75 mph (approx) at 18 Volts on the track. No continuous running here, just a burst to see what the engine could do.

I suppose that the next step is to disassemble and confirm the final drive ratio. An 18:1 ratio is about perfect, but I have several engines at 12.5:1 that I operate at reduced voltage and both the motors and their headlights have never failed. An old GE associate who worked at GE Lighting  once told me that for every 10% reduction below rated voltage of an incandescent lightbulb, the life of the bulb is increased by a factor of ten. A good rule to live by......

I disassembled the engine and confirmed that the final drive ratio is 25:1. See attached image and the black dot on the gearbox input shaft. I counted the number of rotations required for one complete driving wheel revolution.  Knowing the exact length of my track and the circumference of the Niagara driving wheel and the speed at 12 VDC for one trip, I was able to calculate the motor rpm at 12 VDC, which is 4733 rpm. I think I have a 4800 rpm motor. I could replace the motor with a Pittman 9534 (5980 rpm), or use a double threaded worm.

@Hudson5432 posted:

I disassembled the engine and confirmed that the final drive ratio is 25:1. See attached image and the black dot on the gearbox input shaft. I counted the number of rotations required for one complete driving wheel revolution.  Knowing the exact length of my track and the circumference of the Niagara driving wheel and the speed at 12 VDC for one trip, I was able to calculate the motor rpm at 12 VDC, which is 4733 rpm. I think I have a 4800 rpm motor. I could replace the motor with a Pittman 9534 (5980 rpm), or use a double threaded worm.

I wouldn’t mess with the gear box at 25:1. Beings you have it apart, I’d go ahead and stick the Pittman in, and test it, ……you might get close to 12-13V to get some passenger train speeds, but the Pittman will take it, …..I routinely punish those motors in express service……

Pat

@Hudson5432 posted:

So it looks like my choices are to either operate the motor in excess of 12 volts or install a double threaded worm. I know that a 15-20% overvoltage on an open frame USH motor will throw a winding...not sure about can motors.

IMO a double-threaded worm would make it run way too fast while also reducing your wheel torque by a factor of two.  My guess is that the permanent magnets in your KTM can motor might have lost some of their strength over the years, and a fresh Pittman will restore the missing pep.  To answer your question directly, the attached image is a screen capture from the FAQ on the Haydon Kerk Pittman website.  It states that it's generally safe to operate one of their can motors at up to 125% of rated voltage.

https://www.haydonkerkpittman....ush-brushless-motors

(click the grey box that reads "Do I have to run a motor at the rated voltage?")

For reference the FAQ also states that for brush motors, it's best to maintain at least 1000 RPM.  That's one of the reasons that I'm a fan of a low gear ratio--it lets the motor spin at slow track speeds, as opposed to using closed-loop electronic control to batter it with pulses of high voltage, which force it to run slower than it otherwise could.  FWIW.

Thank you for the info.  I have Pittman can motors in all of my engines except two, and the freight engines retained their standard 25:1 final drive ratio. The passenger engines, however, all have double threaded worms. I have a large layout with four mainline tracks and my largest radius is 78-inches, so higher speeds are the norm for passenger service.

I have a few what I believe are good reasons for using double threaded worm gears:

The motors run slower and smoother with lower vibration since I normally operate at 8-9 VDC and a scale speed of about 60-65 mph for passenger.

I have a Joe Fischer train with original lighting, consisting of qty 4, 3 volt bulbs per car wired in series. 3 V screw-in mini bulbs are getting scarce, and I hate to disassemble a car to replace a bulb, hence the operation at reduced voltage.

I also dislike replacing a headlight bulb on a painted engine. Removing the smokebox front risks ruining the paint.

My passenger engines all start at about 2 volts, and have sufficient motor torque to start and haul 18 passenger cars with no problem. The amount of time I am lower than 1000 motor rpm is low.

My operation is up to 12 VDC using Bridgewerks power supplies, and there is no indication that these pulse the motors. There are no electronics in my engines and no electronic control.

I agree with you that a deficiency in this particular can motor is the probable reason for the substandard performance of this engine. After I do some more work on this problem, I will post the results. Thanks again.