Home Free Lab ReportsAbstract Today’s world requires speed on each and every field

Abstract Today’s world requires speed on each and every field

Abstract

Today’s world requires speed on each and every field. Hence rapidness and quick working is the most important. Gearless transmission mechanism transmits power from input to output shafts by means of sliding links that form revolute pair with the hub. The gearless power transmission for intersecting shaft is a device for transmitting motion between the intersecting shaft with angular misalignment. Links bent at required angle slide inside the holes in the hub. Thus, as the holes in input hub rotate; it pushes the links and in turn output hub is rotated. This mechanism can be used as a replacement for bevel gears in low cost, low torque applications. It can transmit at any angle 0 to 180.The gearless transmission for parallel shaft is a device for transmitting motion between the parallel shaft. The minimum number of link required are three for continue smooth power transmission.
Chapter 1

Introduction :

Now a days power transmission device has heavy construction ; heavy weight which reduces the efficiency of prime mover. So we research about to reduce weight ; search about the mechanism which transmit the motion without gear. We decided to develop the mechanism which can transmit the motion without inclusion of gear.
Gear-less transmission is a compact and portable equipment, which is skillful and having something in practice in the transmitting power at right angle without manufactured and can be made in less time. This project uses EL-Bow mechanism which is an ingenious link mechanism of slider and kinematic chain principle. This is also called as “gear less transmission mechanism” and is very useful for transmitting motion at up to 180 degree.
Our mechanism has minimum 3 sliding pairs.This whole assemble is mounted on brackets wooden table. Power is supplied by an electric motor.
The links or rods are free to rotate and slide in the hole, which are drilled parallel to the axis of shaft. The angle for links must precisely the same for each one, and holes in the hub must be accurately drilled. This is very smooth acting device and minimum power loss
Design calculation:
1) Electric motor:
12V DC gear motor.
60rpm
Torque:20Kg.cm

2) Design of shaft:
Mild steel is used for shaft material
Maximum Tensile stress: 70MPa 70N/mm2
Maximum Shear stress : 40MPa 40N/mm2

3) Considering 25% overloading

Tmax.=T*1.25
=20*1.25
=25 kg.cm
=2500 N.mm
Consider 25% over load
Tmax.=2500*1.25
=3125 N.mm
Shaft is subjected to part torsional stress,
T =(?/16)*?*d3
d3=(16*3125)/(?*70)
=227.79 mm
d= 6.10 mm

taking factor of safety =2
d= 6*2
=12 mm
Now consider total torque is also transmitted to the link,
T = 3125/3
=1041.66 N.mm
T = (?/16)*d3*?
d3=(1041.66*16)/(?*70)
=16666.67/2198.8
d3=75.82
d=4.232 mm

we have consider factor of safety = 1.8
d = 4.232 * 1.8
= 7.61
= 8 mm

We know the total 20 kg.cm torque is applied on shaft so,
Torque =force * distance (radius of shaft)
20 = F*(12/2)
F=3.33 kg
=33.3 N

Now we have assumed force is set on the pulley is 33.3 N
M = Ra*(L/2)
= 33.3*(260/2)
= 4329 N.mm

Bending stress for shaft
?= 32 M/(?*d3)
=32* 4329/(?*123)
=25.53 N/mm2

Allowable bending stress is greater than working stress so design is safe
?a(70) ; ?w (25.53)

design of flexible link
length of link = 140 mm
M = Ra * (L/2)

We have assume that reaction is same on all the link and shaft so,
Ra = 33.3 *w
M = 33.3 (140/2)
= 2331 W.mm

Bending stress of shaft
? = 32 M/(?*d3)
= (32*2331)/(?*83)
= 46.39 N/m2

Allowable bending stress is greater than working stress of link
So, design is safe.
?b (70) ; ?w (46.39)
Advantage:
• High efficiency between input and output power shafts.
• Easy to manufacturing of this mechanism as compare to gear mechanism.
• If one link will failure then we have to change only that link.
• This is a very smooth acting device and power loss is minimum.
• Cost of manufacturing is low as compare to gear manufacturing.
• Portability of parts.
• Power transferred at any desired angle.

Limitations:
• Does not work at very low starting torque.
• Improper hole drilling in hub could pose much problem.
• Sudden load would cause link breakdown.
• Speed ratio is always constant 1:1.
Applications:
• Hand driven machines like juice maker.
• Angular drilling between 0 to 180 degree.
• Movement of periscope in submarines.
• Driving for all kinds four faced tower clocks.
• In slash maker for crush the ice.
• In shutter mechanism for open and close purpose.
Future Scope:
• Scope of this project it can be developed as a transmitting power up to 180 degree.
• In this mechanism we install linear contact bearing on hub for reduce friction then we need little amount of torque for smooth operation.
• We use this mechanism in some homemade application in place of bevel gear.
• This mechanism have low construction cost then we use in low budget application for transmit power transmission.
Summary:
The gearless power transmission mechanism is very easy to understand and low cost required to manufacture as compare to gear mechanism. This arrangement used for any set of diameter with any profile of shaft for skew shaft of any angle but shaft must be having rotational motion about this own axis. This mechanism can be used as replacement for bevel gear in low cost and low torque application. This mechanism can transmit power up to 180 degree. One big advantage is that if any one rod will failure then we have to change only that rod.
Cost Estimation :

Components Price (Rs.)
Aluminum Hub 850
Bearings 160
Bearing mounting 400
Mounting Plate 200
Electric Motor 650
Dia.8 pos bearing 450
20 gauge sheet 520
Angle 1*1 300
Dia. 8 shafting 200
Dia. 12 shafting 100
Nut bolt 150
Other expanse 500
Manufacturing cost 1500
Manufacturing process:-
• Lathe machine:
Turning
Facing
Drilling
Threading
• Drilling machine:
Drill
Taping
• Hacksaw:
Material cutting
• Grinding