# Automatic Gate

1. Jul 16, 2012

### arvindrazdan

I need to automate a gate that is 4.91mtr in length, the motion should be swing type and the angle of rotation to be about less than 180 degree. and the mass of the gate is about 300kg, now should I use a dc motor and if so what should be rating of the same, the rpm required about 5-8...

2. Jul 17, 2012

### Danger

Welcome to PF, Arvin.
In this instance, I'd be very much inclined to use a boat-house type of winch with a cable to operate the gate. To simplify things, a heavy spring system could be used for the opposite travel (which way to be determined by whether you want it to be fail-safe or fail-secure).

3. Jul 17, 2012

### Mech_Engineer

Most large gates like this utilize a 4-bar mechanism and gearmotor to operate them. Are you familiar with either of these?

4. Jul 30, 2012

### arvindrazdan

but in four bar mechanism the rod that will be supplying power from the motor has to be of a large length as the length of gate is about 4.9mtr. so it will definetly create a bending in it.....
what will be the hp required if a dc motor with worm gear arrangement is placed on the supporting or on the axis of rotation of the gate

5. Jul 30, 2012

### Mech_Engineer

Honestly it's just an engineering design problem, there's nothing preventing the problem from being solved other than your doubts.

Have you researched how existing designs are implemented?

6. Jul 30, 2012

### arvindrazdan

how much hp motor is required if we use an dc motor, and how can we calculate the angular force required for the same.

7. Jul 31, 2012

### Mech_Engineer

Don't worry about the power, worry about the torque. With a gate weight and some basic deisgn of the opening mechanicsm (and speed you want it to open), you can back-calculate the required motor torque and gearbox reduction ratio.

8. Aug 4, 2012

### arvindrazdan

since i am planning to rotate the gate from its shaft .. i have calculated torue from the equation as I= (mh^2)/3 + (mw^2)/12

after that multiplied I with 3.142/2

to calculate torue
as m = 400kg in my case
h=2.5m
w=5m
and angle (alpha)= 90

so torque is 2618 NM

and the power of the motor i calculated from

power (kwh) = torque * 2* 3.142 * rpm / 60000

from which power is 3 .2 kw motor.. can u please tell if the calculations are right