sprocket vs gear box
sprocket vs gear box
(OP)
The reduction ratio needed im our application is 1800.
Following are the ways to do it:
1. Use an AC invertor and bring its speed down to 140rpm. Then use worm reducing gear 60:1 ratio. Then use a sprocket to reduce the speed further by 4.5 ratio to get a final rpm of 0.5 rpm. The motor chosen is 865rpm
2. Use a 1740 rpm motor and use 2 sets of sprocket reduction to get 0.5 rpm and an ac invertor.
3. Use a double reduction worm gear and 865 rpm motor to get the final rpm to 0.5 rpm
Which of the above 3 is the best choice. The output torque required is 16000in-lb at 0.5rpm. Please suggest a choice from the above 3 or any other choice. The motor only runs few seconds only to rotate a dumper manually. So there is no heat problem. Please help.
Following are the ways to do it:
1. Use an AC invertor and bring its speed down to 140rpm. Then use worm reducing gear 60:1 ratio. Then use a sprocket to reduce the speed further by 4.5 ratio to get a final rpm of 0.5 rpm. The motor chosen is 865rpm
2. Use a 1740 rpm motor and use 2 sets of sprocket reduction to get 0.5 rpm and an ac invertor.
3. Use a double reduction worm gear and 865 rpm motor to get the final rpm to 0.5 rpm
Which of the above 3 is the best choice. The output torque required is 16000in-lb at 0.5rpm. Please suggest a choice from the above 3 or any other choice. The motor only runs few seconds only to rotate a dumper manually. So there is no heat problem. Please help.





RE: sprocket vs gear box
Try a hydraulic rotary actuator.
http://www.helac.com/actuators/quickguide.asp
Or a hydraulic cylinder.
Then use a small motor and small pump to drive the slow speed movement.
Ted
RE: sprocket vs gear box
Don
Kansas City
RE: sprocket vs gear box
RE: sprocket vs gear box
Second question is what is the moment of inertia of a 4000lb cuboid with the axis of rotation offest by x inches.
Will the torque required is same if the axis of rotation is x, y or z axis. The cuboid is the cage which tilts/rotates 360 degree. I need the dumper to accelerate from 0 to 0.5 rpm in 3 seconds.
RE: sprocket vs gear box
RE: sprocket vs gear box
I like the idea of using as little mechanical reduction as possible, and I like to avoid chains.
RE: sprocket vs gear box
RE: sprocket vs gear box
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RE: sprocket vs gear box
RE: sprocket vs gear box
RE: sprocket vs gear box
What about AC Invertor? Is it a good idea to use it to reduce the speed by 1/6?
RE: sprocket vs gear box
Russell Giuliano
RE: sprocket vs gear box
Unless you need variable speed, you should just run the motor at its full rated rpm, gear it down and be done with it.
Don
RE: sprocket vs gear box
RE: sprocket vs gear box
Don: I calculated the torque to be 16000in-lb by using the formula:
Torque = mass moment of Inertia * ang. acceleration
Inertia =1/12* mass* (sq. of a + sq. of b) where a and b are the sides of the basket.
The I calculated Horsepower using the formula:
Torque = 5250 * hp/rpm
After I know the torque I can select a gear motor, sprocket or double reducing worm gear. This is why i was asking what is the best choice.
If I just choose a worm gear or sprocket, then I have to use a coupling or chain respectively. What is the easier option in a coupling or chain and sprocket?
RE: sprocket vs gear box
P = Tw (Power is torque x angular velocity)
P = (16000 #-in)*(0.5 rev/min)*(1 min/60 sec)*(2*pi rad/rev)*(1 ft/12 in)*(1 hp/550 ft-lb) = 0.127 hp
Don
Kansas City
RE: sprocket vs gear box
Assuming the basket is 34" high and 40" wide. Assume the mass of the full basket is 4000lb?
RE: sprocket vs gear box
RE: sprocket vs gear box
In addition to the torque caused by the inertial reaction (angular acceleration) you need to consider what torque the contents might cause at different levels of fullness as you tip. Depending on the substance you are dumping, there could be a considerable torque at different fill levels and angles of tip.
A particulate solid, like sand, would only spill at an "angle of repose" so that more sand would end up on one side of your pivot point and its weight would cause a torque. A non-viscous liquid, like water, would be self-levelling, but depending on the shape of the tub and the location of the trunnion, it could still cause a torque. If your pivot was down at the bottom of the bucket, for example, you could have a hefty torque as you tip the entire 4000-lb load!
Don
Kansas City
RE: sprocket vs gear box
The axis of rotation is exactly 19" i.e. centre of the cage.
I just wanna verify my calculations if the part has 4000lbs and it is full. What will be the torque required to rotate it at 0.5rpm in 3s?
RE: sprocket vs gear box
Just my opinion.
Ray
Every once in a while the voices in my head have good ideas.
RE: sprocket vs gear box
This type of question is why there USED TO BE local distributors. A little bit of engineering background with vast product knowledge, to custom tailor the application to the customer, creating the most efficient drive, both in energy usage and initial equipment and operating costs. This commodity has been replaced by your big catalog, and figure it out for yourself
Russell Giuliano
RE: sprocket vs gear box
The question I am trying to get an answer is how do you calculate torque. Please read this thread and answer the question. I donot think I can put this question in bold font otherwise I will.
Russell: What type of gears will the gearmotor have: worm gear, I assume?
RE: sprocket vs gear box
If you had a 4000 lb weight with its center located 19" away from the axis of rotation, then the worst case torque required to start rotating it would be the product of those two numbers, i.e.
T = W x r = 4000 lb x 19 in = 76000 in-lb = 6333 ft-lb
Which is pretty substantial. Maybe I'm misunderstanding the problem.
If you've got a rectangular basket that may be completely or partially full of heavy awkward stuff, you can't assume that it will be, or stay, uniformly distributed throughout the available volume. One bad case would be when it's all jammed up on one side, or worse, in a corner... in which case, assuming that it's all at the edge of the basket is not all that unreasonable.
Of course, it can all spontaneously fall to the other side of the basket, giving you an overrunning torque just as large as the starting torque.
Mike Halloran
Pembroke Pines, FL, USA
RE: sprocket vs gear box
RE: sprocket vs gear box
I donot think we can ignore the inertia in this case.If the weight of the basket is 4000lbs.
T = 4000/12 x (40x40 + 34x34)x 0.017rad/sq.sec = 15617 in-lb i.e.131lb-ft(you can see that this is double). In calculating Inertia we can add to the inertia the square of the offset distance with the load, I mean, 4000x2x2=16000lb-sq.in and the new value of torque will be 1324 lb-ft
Since T =Inertia x angular acc.
Assuming t= 3s N=0.5 rpm ang acc will be 0.017 rad/sq.sec
i totally understand the load will be shifting but the weight will be decreasing as we will be emptying the basket too.
2nd question repeated: if we have a worm gear box and a motor with 2hp attached to it how much hp and torque we loose from the motor to the gearbox motor due to the effeciency of the gearbox? I'll give an example:
If u have a 2 hp motor connected to a worm gear box at 1740 rpm the torque will be 72in-lb. Now what will be the value of hp and torque at the other end of worm gear if it is 60:1 ratio and the effeciency is 35%.
Please see the picture of the dumper
RE: sprocket vs gear box
My car doesn't even weigh 4000 lbs! Are you sure that slotted-aluminum contraption with little bearings will even support the weight?
I think I'm going to run away from this one.
Don
Kansas City
RE: sprocket vs gear box
Ron Volmershausen
Brunkerville Engineering
Newcastle Australia
http://www.aussieweb.com.au/email.aspx?id=1194181
RE: sprocket vs gear box
Why is the full rotation required?
Ron Volmershausen
Brunkerville Engineering
Newcastle Australia
http://www.aussieweb.com.au/email.aspx?id=1194181
RE: sprocket vs gear box
Ron Volmershausen
Brunkerville Engineering
Newcastle Australia
http://www.aussieweb.com.au/email.aspx?id=1194181
RE: sprocket vs gear box
I donot need 360 degree but atleast 270 deg. This we we can insure that there are no parts left inside.
I just need to order few more.so I am looking for best possible way to design the same thing. I need to know what are the different possible ways to achieve this- with worm gear, AC drives, sprocket, may be all of them but what is the best way to achieve the rpm and torque.