Videos

00:05
Rotary valves can jam up causing downtime.

00:09
This is especially true in running sawdust, wood chips, or any pelleted materials.

00:17
First we will look at a standard set up.

00:20
The gear motor is turning a small sprocket which transfers

00:23
its rotation through the chain to the large sprocket.

00:27
The large sprocket drives the rotor.

00:30
A typical speed of the rotor is 20 RPM.

00:34
Here we see a rotor jam occurring.

00:36
The rotor slows down and then stops.

00:39
The large sprocket stops while the motorized small sprocket

00:42
continues to strain.

00:44
This stresses the motor shaft, both sprockets, the chain and

00:48
the rotor shaft.

00:51
The chain breaks.

00:56
Even a slight bend in the shaft makes the rotor unusable.

00:59
Same for the motor.

01:02
Here we have isolated the large sprocket and we'll look at a

01:05
better alternative.

01:07
This simple sprocket will be replaced by a shear pin

01:10
sprocket.

01:13
The shear pin will break before the chain breaks or any shafts

01:17
bend.

01:18
Let's look at the components of the shear pin sprocket.

01:25
In this exploded assembly, Note 3 critical parts: shear pin, hub and sprocket.

01:33
The shear pin is the key to this improved system.

01:37
This tiny waist will shear before any damage is done to the

01:41
chain, motor, sprockets or rotor.

01:45
The shear pin waist, which has a calculated diameter based on

01:48
load conditions, is ready to shear.

01:51
Think of it as a fuse in an electric circuit.

01:54
Let's reassemble the shear pin sprocket and see it in action.

02:01
The simple sprocket is now replaced by the shear pin

02:04
sprocket assembly.

2:07
If the shear pin breaks, the large sprocket continues to spin

02:10
but it's hub will stop.

02:12
This protects the chains, sprockets and more importantly

02:15
the motor and rotor shafts.

02:18
It's a good idea to have a zero speed switch attached to indicate stoppages.

02:24
Here the shear pin sprocket is in place and ready to run.

02:29
Now we are back running at 20 RPM.

02:33
At the start of any jam there is a very slight strain on the

02:36
chain.

02:37
Note that the shear pin is feeling the strain as well.

02:42
The shear pin is now experiencing its breaking torque.

02:48
The shear pin breaks but the large sprocket continues to spin, freewheeling.

02:55
Only its hub is stopped and this protects the chain and more importantly the motor and rotor shafts.

03:01
A zero speed switch will signal that the valve is down.

03:05
Before proceeding, lockout the power, then free up the jam.

03:10
Push out the shear pin remnants and replace with a new shear pin.

03:14
The alternative that avoids chain breakage and stops permanent

03:18
damage to the sprockets and shafts.

03:23
If you have any questions please contact us.

03:26
Contact information is on our website www.acsvalves.com.