PDSGB (Propulsion Dynamics Steel Gearbox and HL "Dual Current" Gearbox Discussion

[Rubicon99]

I don't have the HL sprocket yet and do not understand the need to file down the gear shaft. The Mato sprocket had no problem with the Taigen gear shaft. The screw hole on the outer sprocket half is for the HL/Mato 1/8" machine screw. Taigen Tank gear shaft has 3/16" machine screw thread. It comes with the matching machine screws. But the 3/16" screw is too big to pass through the 1/8" hole on the sprocket making it necessary to drill it out to 3/16" inch.

The HL, Heng Xin and Taigen gear shaft for Pershing all measured to 0.321". The HL sprocket should fit over the Taigen shaft just fine.

Got slightly ahead of where you were at in the process. In general HL sprockets are not direct drop on to Taigen drive shafts some are to loose some are to tight. It is well known they need “fitting”. Yes you have to open the screw whole a small amount to fit the Allen screw but that is often not enough. You might get lucky and receive a sprocket set that fit, then again you might not. The tolerances in HL sprockets do very a bit. I have been down that road far to many times not to give someone a friendly heads up and a solution to it that is commonly known vs letting them be surprised.

So should your incoming HL sprockets not fit you now know the common method used to make them fit.

[keilau]

Got slightly ahead of where you were at in the process. In general HL sprockets are not direct drop on to Taigen drive shafts some are to loose some are to tight. It is well known they need “fitting”. Yes you have to open the screw whole a small amount to fit the Allen screw but that is often not enough. You might get lucky and receive a sprocket set that fit, then again you might not. The tolerances in HL sprockets do very a bit. I have been down that road far to many times not to give someone a friendly heads up and a solution to it that is commonly known vs letting them be surprised.

So should your incoming HL sprockets not fit you now know the common method used to make them fit.

After reading your #19 post, I mic the motor shaft of the gearboxes that I have. Including the Taigen, they are very standardized 0.321" in diameter. I have one HL, one Torro and 3 Mato sprocket which all fit the gearbox with no problem using 1/8" machine screws.

My Pershing metal sprocket are 14 years old. It fits over the Taigen shaft fine, but the machine screw hole is too small. But I broke it and am now waiting for a HL sprocket set because Taigen is sold out. I will let you know how the HL sprocket fits.

[tank_me]

Do you have any idea on how to compare the quietness of gearbox?

With the HL stock steel gearbox, the engine simulation is struggling to be heard. After I switch to the Heng Xin gearbox, I hear the simulated engine sound clearly and can turn it way down when playing the tank indoor. This is very subjective.

I am halfway through my Sherman metal conversion and start think of the next project. The HL CNC gearbox is one possibility. But I cannot find any information such as the voltage rating and rpm of the 550 motor used. I suppose that it is a brushed version. It would be nice to know the manufacturer and model number.

I don't hear any gearbox noise out of the HL CNC gearboxes. All you hear is track noise even with the sound disconnected. I have a set of these installed in my Taigen hulled KV-1E and my Taigen hulled SU-152. I have another set to be installed in my HL Pershing project.

[JennyC6]

That fancy gearbox looks like a godsend for more modern/sophisticated tanks, but I wonder if this fancy gearbox can more accurately replicate the hurky lurchy jerky movement of WW2 era Soviet tanks.

WW2 Soviet tanks did not have any chance whatsoever of being smooth. They lurched and lumbered. Their transmissions were incredibly crude, simple, basically a truck transmission with a locked diff and clutch/brakes on each output shaft.

On my KV-1E 7.0 I disabled pivot steering which helped a ton, but it's still too smooth for scale movement. If this new gearbox can more accurately replicate that I might be willing to install one at some point. 'Course it's also entirely possible that the models are just too light to lurch around, and if so oh well.

I don't hear any gearbox noise out of the HL CNC gearboxes. All you hear is track noise even with the sound disconnected. I have a set of these installed in my Taigen hulled KV-1E and my Taigen hulled SU-152. I have another set to be installed in my HL Pershing project.

Can confirm. My...admittedly brand new...7.0 HL KV-1E's transmission is pretty much inaudible over all the track clatter, especially on hard surfaces like my kitchen floor. Those tracks are LOUD.

[Timbo68]

I have one of the HL ‘dual current’ gearboxes, which I bought for a project, mainly out of interest. However, it’s big, and wouldn’t fit. It’s now in a T-72, which took quite a bit of drilling and fitting. It works, but, TBH, I don’t think it’s any better or worse than a good ‘standard’ metal box. It does have a tendency to whine when power is applied, but this is lost once the drive starts. Shafts of different lengths are available. It was quite a bit of money for an experiment…

[tank_me]

That fancy gearbox looks like a godsend for more modern/sophisticated tanks, but I wonder if this fancy gearbox can more accurately replicate the hurky lurchy jerky movement of WW2 era Soviet tanks.

WW2 Soviet tanks did not have any chance whatsoever of being smooth. They lurched and lumbered. Their transmissions were incredibly crude, simple, basically a truck transmission with a locked diff and clutch/brakes on each output shaft.

On my KV-1E 7.0 I disabled pivot steering which helped a ton, but it's still too smooth for scale movement. If this new gearbox can more accurately replicate that I might be willing to install one at some point. 'Course it's also entirely possible that the models are just too light to lurch around, and if so oh well.

Can confirm. My...admittedly brand new...7.0 HL KV-1E's transmission is pretty much inaudible over all the track clatter, especially on hard surfaces like my kitchen floor. Those tracks are LOUD.

Having driven a Sherman from WW2, more modern Vietnam era tracked vehicles (M42 Duster and M114), and ridden in many others while volunteering at the museum, I can say that the normal person probably wouldn't comprehend the amount of work it is to drive a vintage tank. None of the vehicles I've driven was capable of a neutral turn so the forces that brake one track for turning aren't gentle. It also requires a lot of throttle to turn. Riding in a T-34/85, I watched the driver doing a body weight shuffle to yank back and hold the driving yolks to turn. It didn't look easy for sure. The M42 Duster was a cold blooded tank if I ever saw one. You couldn't even get it to move straight if it wasn't warmed up for at least 20 min. More modern tanks are smoother, but even modern Russian tanks are not that smooth.

Disabling neutral turns (or pivot turning) does help make the driving look a little more accurate, but as you said it doesn't even come close to the real thing.

[JennyC6]

Having driven a Sherman from WW2, more modern Vietnam era tracked vehicles (M42 Duster and M114), and ridden in many others while volunteering at the museum, I can say that the normal person probably wouldn't comprehend the amount of work it is to drive a vintage tank. None of the vehicles I've driven was capable of a neutral turn so the forces that brake one track for turning aren't gentle. It also requires a lot of throttle to turn. Riding in a T-34/85, I watched the driver doing a body weight shuffle to yank back and hold the driving yolks to turn. It didn't look easy for sure. The M42 Duster was a cold blooded tank if I ever saw one. You couldn't even get it to move straight if it wasn't warmed up for at least 20 min. More modern tanks are smoother, but even modern Russian tanks are not that smooth.

Disabling neutral turns (or pivot turning) does help make the driving look a little more accurate, but as you said it doesn't even come close to the real thing.

Oh I don't doubt that in the least. You can see just how crude it is to steer them by watching how much all that armor lists and pitches whenever they're steered. The Soviet stuff seems the worst of the lot, but I don't see tanks steering proper smooth until well into the Main Battle Tank era. The M1 Abrams, Leo 2, Challenger 2, T-90, Type 10, stuff like that steers as smooth as a pickup truck despite weighing as much as a King Tiger. Steer by wire, stupid amounts of power, advanced transmissions that can actively power both tracks at different speeds up to and including opposite directions...stuff that wasn't possible in the 1940s. Nazi Germany tried but it was a sure-fire way to break something; it's telling that Bovington has never pivot steered Tiger 131 even though 131 should be capable of doing so.

I've heard some T-34 drivers had to use sledgehammers to help them change gears because the tanks were so crudely built! Is common for them to have to use both arms on the steering levers to steer them even today when the tanks are kept in far better condition than could ever have been dreamt of back in the war. And in the videos I linked you can hear how hard the driver has to lean on the engine to get a turn out of the tank, especially the heavier KV and IS tanks.

I'm a bit surprised the vietnam era stuff was still just as rough to drive. One would think 30 years of tank transmission development would have at least given them power assist on the steering levers. By that point power steering and brakes were available on most passenger vehicles, commercial vehicles, soft-skinned/wheeled military vehicles.

Side note, it kinda puts some perspective onto what the kids that drove these things into battle were dealing with. They're a pain in the butt to drive today. Thinking about dealing with that, but in less-than-ideal condition and while being shot at by things that could probably penetrate your armor....

[tank_me]

The really funny thing is that the shocks used on a Sherman HVSS are commercially available today since they are farm tractor shocks. There are a lot of parts that are still produced from WW2 that have been integrated into modern US vehicles. The engine starter switch, headlights, and tail lights to name a few are very similar to their WW2 counterparts. The M42 Duster is based on the M41 Bulldog hull. The M114 and the Duster use a T bar for steering. The T bar itself was easier to actuate than the steering yolks on a Sherman, but the low engine power makes turning difficult. It doesn't surprise me at all that armored vehicles hadn't advanced much since WW2, but you have to look at the fact the US didn't see a need to develop a bunch of armored vehicles until the Korean War which is why they were still using Shermans and Pershings. US doctrine changed into one of deterrence during the cold war. Prior to that most of the military technology advances were as a direct result of a war or conflict. Development times in time of war are extremely short. Development times in peace time are very long. The Abrams design process starting in 1972 and didn't complete until 1980 when it entered US military service.

[keilau]

I will not be able to finish the Taigen gearbox until later. I did not realize that Taigen uses 3/16" sprocket mounting screw vs. the 1/8" screw used by HL and Mato. No big deal. I just drill out the old Mato sprocket hole to 3/16". It should be easy because Mato use very soft metal cast. I made the big mistake of NOT clamping down the sprocket on the drill press and just held it by hand. The sprocket flew away and chipped 2 teethes. I was very lucky that I did not get hurt. Lesson learned.

The Pershing sprocket is sold out at Taigen. I ordered a pair of the HL sprockets from Toucan to be shipped from China. It should work fine as the track are rubber padded HL track. The hole just needs to be enlarged. Will hold the part down properly this time.

I will drill out the HL plastic sprocket to test out the setup. The Toucan order probably won't be here until December.

The HL sprocket for pershing arrived in 9 days. Toucan is quite fast even when they do not have stock in the US. I ordered 2 pair and drilled out one to the M5 screw hole that Taigen requires. The second pair is keep with the M3 holes in case I want to go back.

The HL casting quality is not up to the Mato or Taigen/Torro standard. One of the sprocket fits over the gearbox shaft out of the box, but the second one did not. I have to file the socket edge slightly and lubricate the inside. It is a tight fit but works. I fired up the Taigen gearbox with the red 390 and get a scale speed of 36 mph. It is much faster than the Pershing's 26 mph sustained and 30 mph dash. The previous Tamiya380 and Heng Xin gearbox got 26 mph. I found the Taigen gearbox much quieter and steadier than the Heng Long steer gearbox.

Now, I have the Heng Xin gearbox with Taigen Black 380 motor looking for a home.

[ccarley]

Hey all,

My HL dual current gearbox arrived today and I did the installation this evening in my Abrams. Note, this Abrams has plastic tracks and had the plastic gearboxes. I didn't really have trouble with them but I can say the original motors were noisier than the dual current box.


Had to trim 2 locating nubs for the box (mounting plate) to sit correctly.



Removal of the smoker was just fine since I never used it (and I don't believe the gas turbine smokes much anyway), but I had a heck of a time getting the top of the hull re-installed. The 7.0 board kept hanging up on the bottom of the turret as it does not sit all the way down. It needed to slide back more, so it's kind of next to that 540 motor. There's also a support that I had to remove on the hull top that was hitting that 540 motor. Still seemed tight but I got it all back together without any hangups on the turret.

Now that it's back together, initial (indoor carpet) impressions are, well it's not "fast". It is quieter for sure. It's quiet enough that you can hear the speed control switching now, where prior to this that was overwhelmed by the gear train noise. It seems to be "breaking in" a bit though and within 5 minutes was running a touch quicker and smoother. The turning motor is louder than the drive motor which I expected. The new box came with the axle support bearings (which I had already added) and it seems to have full bearings. I pulled the main drive cover off and you could see a support bearing in there, and it's belt driven.

It's too wet here in Nor-Cal now to be running outdoors for the time being, so that's about it for now. Once it dries out I'll strap the Gopro to it to get some driving sound bits.

Clay

[keilau]

@ccarley, thank you for sharing your dual current gearbox impression. I have been thinking about trying this gearbox on the Leopard 2A6. Does the gearbox make the acceleration more linear? The turns more controllable and realistic? What is the main benefit switching to the dual current gearbox?

I use the Tamiya track with MxFans 390 motor and Heng Xin gearbox. It runs really fast and very quiet and stable. But running it well takes lots of skill which I do not have. I know, I know. It's a hobby for fun only. But making it run better, more controllable for the novice is part of the fun.

[ccarley]

keilau, so far due to the (awesome) amount of rain we received I have not really been able to test a lot yet however I was testing indoors again yesterday and I can say the acceleration is a bit more controllable, maybe not linear but it's like it has some expo built in now. I tend to use little stick movements and with little stick movement now, the tank moves very little.

The turns are in fact different now; of course it can still spin on the spot but on our indoor carpet I do like how it turns. Maybe more realistically. The turning motor is louder than the drive motor and things are still "breaking in" internally. I say "breaking in" only because it seems the bearings may have a touch of oxidation internally or their lube gelled or something; when installing the output shafts, even though they were in bearings, it felt like they were attached to a rubber band for lack of a better term. Like, there was a free spot, but if you turned them one way or the other, they wanted to return to that free spot. But, as I run the tank, they seem to be loosening up.

Perhaps if we get a chance to dry out I can get a video of both the Abrams with this gearbox and my daughter's Leopard with regular steel gearboxes in action at the same time to get some actual info comparing the two. We have the red motors for the Leopard, just not yet installed; that's still a work in progress as I am just getting to painting the metal sprockets for that tank as well.

Clay

[ccarley]

OK, delays due to weather and Covid unfortunately but I finally installed the red motors in my daughter's Leopard.

The Leopard was a basic plastic model but now has metal tracks and metal sprockets. No other metal wheels, but it does have the outer drive bearings. Steel gearboxes although I do not know if they have actual bearings or just (really smooth) bushings, and now of course the red motors.

The Abrams was a basic plastic model, which still has all plastic running gear with the exception now of the Heng Long Dual Current gearbox.

My impressions:
The Abrams has plenty of torque outdoors. It doesn't have a lot more speed, and like I mentioned before the throttle feels like it has expo on it now. You need like 1/2 throttle to get it moving; controlled slow speeds should be pretty easy. This is supposed to be the fast gearbox, according to the numbers, but I recall someone had the fast gearbox but it had the slow gears in it even still.

The Leopard's big issue was a loose motor (!) causing noise, but no driveability issues. The red motors installed are not super loud but that tank, even with it's added weight, is faster for sure. I don't think the red motors have the same torque as the big motor in the Abrams now but it definitely has more top-end in the (mushy) grass.

I can run the volume pretty low on the Abrams and hear it over the motor now; not as much with the Leopard. I'd say the Leopard has to have the volume 1 to 2 notches higher than the Abrams to hear it over the red motors.

Clay

[Rubicon99]

OK, delays due to weather and Covid unfortunately but I finally installed the red motors in my daughter's Leopard.

The Leopard was a basic plastic model but now has metal tracks and metal sprockets. No other metal wheels, but it does have the outer drive bearings. Steel gearboxes although I do not know if they have actual bearings or just (really smooth) bushings, and now of course the red motors.

The Abrams was a basic plastic model, which still has all plastic running gear with the exception now of the Heng Long Dual Current gearbox.

My impressions:
The Abrams has plenty of torque outdoors. It doesn't have a lot more speed, and like I mentioned before the throttle feels like it has expo on it now. You need like 1/2 throttle to get it moving; controlled slow speeds should be pretty easy. This is supposed to be the fast gearbox, according to the numbers, but I recall someone had the fast gearbox but it had the slow gears in it even still.

The Leopard's big issue was a loose motor (!) causing noise, but no driveability issues. The red motors installed are not super loud but that tank, even with it's added weight, is faster for sure. I don't think the red motors have the same torque as the big motor in the Abrams now but it definitely has more top-end in the (mushy) grass.

I can run the volume pretty low on the Abrams and hear it over the motor now; not as much with the Leopard. I'd say the Leopard has to have the volume 1 to 2 notches higher than the Abrams to hear it over the red motors.

Clay

Your two red 390 motors combined produce more power (given that the same voltage is being used in both tanks) as your one 540 motor. In the PDSGB one motor is for forwards/back movement the other is for turning. So in all out straight drag the dull 390 motors will outperform the signal 540 almost ever time.

[ccarley]

That stock silver can 550 motor really wasn't cutting it for me. It needed like 1/3 throttle before it would turn... I pulled it out and it acted pretty much the same way. It hummed, and didn't do much. It would spin up at full throttle no problem. I pulled the "flux ring" off, and similar results; it spun faster but not by much. After some internal debate, I ordered a 21-turn 550 motor as I recalled from my old RC car days, I thought that should be pretty safe.

https://www.amazon.com/gp/product/B09XK8C7H3/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Installed tonight and YES it responds to minimal throttle input much better, and has more top speed. My WWII tanks crawl and in my opinion they look good doing that; the Abrams (and the Leopard) look good at speed soaking up the bumps, and they will be out in the sand.

The HL gearbox I purchased is the plastic unit with steel gears (confirmed when I had it out tonight). I did get it when the price was much lower than it is now... so I'm not crying about it. With the current prices I've seen, the red motors on steel gearboxes are most definitely the cost effective way to go. The turning is very very smooth though with this gearbox. I did also stiffen the rear most suspension arms as the torque was making the tank squat too much. I also decided to add a pound or more of weight to the front of the hull for some better fore/aft balance since this gearbox does add weight, and I do not have metal tracks.

Clay

[keilau]

ccarley, you convinced me to keep my twin 390, Heng Xin gearbox setup for the Leopard 2A6. Per @Robincon99, it is more powerful powerplant and more responsive to driving control too.

[keilau]

The HL sprocket for pershing arrived in 9 days. Toucan is quite fast even when they do not have stock in the US. I ordered 2 pair and drilled out one to the M5 screw hole that Taigen requires. The second pair is keep with the M3 holes in case I want to go back.

The HL casting quality is not up to the Mato or Taigen/Torro standard. One of the sprocket fits over the gearbox shaft out of the box, but the second one did not. I have to file the socket edge slightly and lubricate the inside. It is a tight fit but works. I fired up the Taigen gearbox with the red 390 and get a scale speed of 36 mph. It is much faster than the Pershing's 26 mph sustained and 30 mph dash. The previous Tamiya380 and Heng Xin gearbox got 26 mph. I found the Taigen gearbox much quieter and steadier than the Heng Long steer gearbox.

Now, I have the Heng Xin gearbox with Taigen Black 380 motor looking for a home.

After I completed the conversion to the Torro Version2 ball bearing steel gearbox, I did not test it outdoor due to winter time in Chicago. After a few runs on smooth concrete floor, I noticed excessive wobbling of the right metal track. At first, I suspected a defective gearbox from Torro. The gearbox is in perfect condition after I removed them from the tank. During the removal process, I noticed 2 of the mounting screws were not as tight as it should.

Heng Long use M3 self tapping crews for gearbox mounting. The Pershing was purchased in 2005, After 18 years, 2 of the mounting posts crack making it impossible to tighten the screws. The gearbox came loose and causing the track to wobble. I drilled through the bottom of the post and tap the inside for M3 machine thread. I mounted the gearbox with 6 pair of nut and bolts. There is no question that the posts are still stronge enough to hold the gearbox. The nut and bolt set make it very stable.

I cannot blame HL for the post cracking problem. Over the years, I went through the HL original plastic gear, Tamboy (German store) cast metal gear, Heng Xin steel gear and the Torro steel gear. I am happy that the HL chassis holds up as well as it does.