Modifying Parker Cylinder

[Coachmac]

I have searched and searched, can't find anything about this. For our arm, we are looking at using the van door motor and mounting the Parker cylinder to it. Is it against the rules to bore out the mounting pin on the end of the cylinder? We are wanting to bore that out and mount it directly to the shaft of the van door motor. Is this allowed? Also, any weaknesses to the van door motor we should know about? Thanks

[Mike Betts]

You do not have to bore it out. A good arbor press or even a vice (properly fixtured) will push out the mounting pin.

[dlavery]

From rule <R85>:

Pneumatic components supplied in the Kit compressor, regulators, pressure switches, cylinders, valves, fittings, tubing, etc.) may not be modified except as follows: ... Mounting and connecting pneumatics components using the pre-existing threads, mounting brackets, etc., is not considered a modification of the components. Removing the pin from the rear of an air cylinder is allowed as long as the cylinder itself is not modified.

So, yes, you can remove the mounting pin. However, if you are going to place the cylinder on the output shaft of the van door motor (in the place of the pin), then be sure that you are properly supporting the output shaft itself against excessive side loads (i.e. support the shaft on both sides of the cylinder if it will be pushing against the shaft) and rotational friction problems (i.e. protect the output shaft in the mounting pin hole from rubbing directly on the hole without an appropriate bearing surface).

-dave

[Adam Krajewski]

Originally Posted by Coachmac

Also, any weaknesses to the van door motor we should know about? Thanks

The brake on the van door motor can be used to provide a slight amount of back-drive resistance, but it will NOT be able to handle a large load. It will eventually fail. Any design utilizing the brake should be followed VERY cautiously.

[Coachmac]

Originally Posted by Adam Krajewski

The brake on the van door motor can be used to provide a slight amount of back-drive resistance, but it will NOT be able to handle a large load. It will eventually fail. Any design utilizing the brake should be followed VERY cautiously.

We had not planned on using the brake on the motor. In fact, I didn't know it had a brake on it. Does that brake have to be disabled? How do we go about doing that? We had simply planned on using the motor to drive our swing arm. Is there another motor that would be stronger/better to use?

[Andy Brockway]

<R85> allows you to remove the pin but you are not allowed to "file, machine or abrasively remove any part of an air cylinder".

So you cannot enlarge or machine for a key. You can bush if the original hole is larger than the motor shaft. You cannot machine the hole larger if it is too small. Pressing the cylinder onto the shaft 'as is' could fall under the "abrasively remove" clause.

[scifi3018]

Make a mounting bracket to fit onto the pin then have a larger hole.