Shifting Gearboxes

[pmangels17]

We always use a double solenoid, and we also use plumb both shifters to one valve so they throw at the same time. Please remember to USE PNEUMATICS TO SHIFT. Servo shifting is pure garbage and wont work under the the slightest pressure against the side of a dog, such as when pushing.

We usually start in low gear, and use high gear when we want to go really fast.

We have never tried using ball shifters, but since we have familiarity with the dog shifting style used in AndyMark gearboxes, and it has proved reliable so far as a shifting method, that probably won't change. Dog shifting is proven and tested, but ball shifters have been generally well reviewed as well, though they may be harder to implement in a custom gearbox.

[markmcgary]

Originally Posted by AdamHeard

Why not use singles? Doubles waste an extra relay output.

We have yet to graduate to two-speed gearboxes. But, we have used pneumatics in each of our two years. When you speak of 'single solenoids' and 'double solenoids', I assume these are matched up with appropriate cylinders.

'Single Solenoid' working with a 'Single Acting Cylinder' (Spring-loaded).
'Double Solenoid' working with a 'Double Acting Cylinder'.

I can see a Single Solenoid, feeding two Single Acting Cylinders working for shifters.

Do I have this right?

[AlecS]

Originally Posted by markmcgary

We have yet to graduate to two-speed gearboxes. But, we have used pneumatics in each of our two years. When you speak of 'single solenoids' and 'double solenoids', I assume these are matched up with appropriate cylinders.

'Single Solenoid' working with a 'Single Acting Cylinder' (Spring-loaded).
'Double Solenoid' working with a 'Double Acting Cylinder'.

I can see a Single Solenoid, feeding two Single Acting Cylinders working for shifters.

Do I have this right?

The terminology here refers to the number valves/ports the solenoid valve has.

A single solenoid has one valve, and two ports. (Port A and Exhaust A.) When you apply voltage to the solenoid it switches between EA and A, or vise versa. This means you can control two lines of air, by plumbing them to A and EA, as long as the robot is enabled. When it is disabled, no voltage can be applied and it will default into one port. In practice this means you can control a double acting cylinder, as long as you are fine with it defaulting into one position all the time, as the default can only be changed by plumbing.

A double solenoid has two valves are 4 ports. (Port A, Port B, Exhaust A, Exhaust B). The solenoid has two control inputs, and can control both A,EA and B,EB. It typically controls two lines of air by plumbing them to A and B, and venting/plugging EA and EB. In practice this means you can control which way a cylinder defaults when disabled, without having to re-plumb the cylinder, as you have two valves to control. You can also use double solenoids to provide a "neutral" position, where no air is supplied to the cylinder.