Reply With QuoteFirst, I would look at the equations and calculate a few scenarios with the following calculator:
Screw Gear Axial Force Calculation
Hi Folks
I'm wanting to apply a new concept to something we have already been doing. Original design is lead screws lifting an element like a cross par for adjustment by hand crank. lead screws are vertical an tied by roller chain and sprockets. On some units across the bottom top or even in the middle. The goal is to provide lifting and fine adjustment to a horizontal element that weighs about 60 lbs.
I the new unit I want to have 2 vertical elements with gear rack on each. (in parallel and rigidly attached) and sliding elements incorporated to hold fast any other forces in other directions other than vertical. On the horizontal element that will be raised and lower there will be a drive shaft 1" in diameter with spur gear on each end to engage the racks (rack and pinion gears basically)
to drive this up and down (the 60lb load) I want to have a 4" Diameter gear with a worm to engage it and be operated by the crank. I picked 4" because I felt it would be strong enough for the load required and lessen the effort on the hand crank which will have a 7" swing. The problem is I'm unsure of the calculations I used to arrive at my estimates here and want this unit to last as long as the lead screw unit did. Any experienced input would be helpful.
Thanks
Glenn
Last edited by GlennD; 03-29-2014 at 01:40 PM.
First, I would look at the equations and calculate a few scenarios with the following calculator:
Screw Gear Axial Force Calculation
Last edited by Kelly_Bramble; 03-31-2014 at 02:18 PM.
oh I also see I have to worry about axial thrust forces on the worm wheel shaft. I don't have a way to counter that yet.
Perfect Kelly thanks. I hadn't seen that calculator on the site.
Gear manufacturer came back to say that without an oil bath the gear wear will be excessive (we have a working mock up on the floor now). I pointed out that hand winches in continuous use lasted, with greater loads, many more years than we expect here in an application that may be used twice a day at most and at less than 3 RPM with what turned out to be 55ft-lb or torque . But I can't really argue this point as I have no way to calculate wear on this device I only have anecdotal examples like my winch above.
I really don't want to introduce a gear train into this to overcome the back drive forces. One of the requirements for the design is that the crank arm be able to be operated from either side of the unit. This was easier in the lead screw unit because they could swap cranks from one side to the other easily when the machine is first installed. My original concept would have necessitated swapping the whole shaft and they saw this is unacceptable hence the worm drive in the middle. I am so far out of ideas that would fit in the space required and will have to resort to the chains and lead screws that they are used to.
wow. ok I just spoke to them (the gear people) they have no idea, They just told the client this because when gearboxes run out of oil the gears fail. They no longer have anyone on staff that can advise on this they only have whats in their catalog.
hello..i need to design a compound gear train whose train ratio is to be 10:1. the motor shaft rotates at 100 rpm and torque is 10nm..kindly help me to design the gear train..if needed more details kindly ask me....
thanks in advance
sivaranj
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