Mounting Planetary Set Between Two Pinions

[BrentimusMaximus]

I'm currently studing options to retrofit a drive train for a tipping mechanism on a slag haulage car. The slag pot tipping mechanism consists of a parallel gear train driving a worm that rotates a pinion on a rack, which is fixed to the slag pot. So, the slag pot rolls on a rack and pinion to dump the load. This means that it translates and rotates simultaneously to dump the slag. One of the options I've proposed is to remove the existing drive train and add another rack and pinion with a top-mounted rack that runs parallel to the exing one. I would then mount a hydraulic geared motor (planetary set) between both pinions, keeping it free from the frame of the car. So, the motor freewheels between the pinions. Since the second rack is top mounted, it compensates for the direction opposition.

One of my colleagues believes that this is not technically feasible, since one pinion would rotate faster than the other and bind the system due to the gear ratio developed in the planetary set. However, I'm having trouble visualizing this. As far as I can see, there will be a relative difference in velocity between the input and output. Since the input is mounted on one pinion and the other is mounted on the second pinion, I believe the system will balance itself out, since each pinion should share the torque equally. I don't believe that one pinion will rotate faster than the other, since the motor is not fixed to anything other than the pinion.

Can anyone weigh in on this? Has anyone ever done this?

 

[mikekilroy]

i think i here u saying u see benefit of having one motor run thru a planetary gearbox then drive two pinions.

what benefit do you see in driving 2 pinions from the same planetary fed motor? I don't see any at all. why not just use 1 pinion of the proper size?

 

[BrentimusMaximus]

In this configuration, you would need two pintions, since the motor has to translate with the slag pot as it rotates and translates.

 

[imcjoek]

We need a drawing for this one. I tried to visualize this from your description and quickly wound up somewhere between Escher and Golberg.

 

[BrentimusMaximus]

Can I attach an image here?

 

[imcjoek]

Yes,
See the bottom of the reply box "Attachment: ...or upload your file to ENGINEERING.com"

 

[BrentimusMaximus]

These are two screen captures of my model. Please note that the second top-mounted rack would be fixed to a frame. I put it there for concept visualization.

 

[BrentimusMaximus]

Sorry I didn't realize I could only upload one at a time. Here's the second.

 

[imcjoek]

Well, that's somewhat better.

But I'm still lost on this bit...

I would then mount a hydraulic geared motor (planetary set) between both pinions, keeping it free from the frame of the car.

My understanding is that the existing system has only the bottom rack, and the motor drives the pinion on your giant teacup. IE: Motor moves with the slag pot. I don't understand your proposed new drive system. It's going to drive both pinions? Aren't they already affixed on a common shaft?

Ignoring how you drive this for now, and assuming the pinions are fixed to a common shaft:
With the pinion shaft driven at angular speed w and gear pitch diameter Pd,
The pot will translate at w*Pd/2.
The top rack will translate in the same direction at w*Pd. (Twice as fast)

 

[BrentimusMaximus]

But the pot is mounted rigidly to the same shaft as the pinion.In that case, there is no reduction. The pinions are simply acting as rollers. So, by definition, it would have to rotate at the same angular velocity??

 

[imcjoek]

But the pot is mounted rigidly to the same shaft as the pinion.In that case, there is no reduction.

The pot will rotate along with the pinions.

I would then mount a hydraulic geared motor (planetary set) between both pinions

What does this mean?
The hydraulic gear motor has an output gear that is wide enough to engage both pinions?
What does the second pinion and rack even do? If that rack is grounded, the entire thing cannot move.