# What will be required torque for motorised spool.

1. Oct 15, 2013

### mandarz

For selecting motor... I need to calculate torque for motorised spool used to wind 5KM of fiber optic cable.

Cable O.D. 4mm.
The distance between flanges is 520mm.
Flange O.D. 650mm.
Application of spool is only reeling and unreeling. While unreeling will be done by manually.
Assume empty spool weight 20 Kg.
RPM=50

What will be torque and power rating?

2. Oct 15, 2013

### Simon Bridge

Welcome to PF;
At a constant speed - you only need torque for pulling the load and overcoming friction.
So you need the worst case mass of the entire unwound cable.

The dimensions of the spool are important - a large diameter spool needs more torque, particularly to accelerate.

The acceleration is important too - how fast do you want the spool to pin up to top speed?

If you already have a spool - turn it with a torque wrench and see.

3. Oct 15, 2013

### mandarz

Thanks Simon !

We dont have spool at the moment.

We are considering stall torque motor for reeling (Are you agree on this?, According to you selection of motor should be on what basis for this application?) .

Cable will be wind over 240mm barrel diameter.

4. Oct 15, 2013

### Staff: Mentor

Welcome to the PF. You are supposed to show your own attempt at the solution when asking for help here on the PF. Please check your PMs.

5. Oct 15, 2013

### mandarz

Thanks Berkeman,

I have calculated as
1) T=F x r

where
F=ma

a=v square/r

v=pi x Dx N/60

power=force x velocity

with applying MKS units.. I calculated power as 0.443 KW.

Is this correct?