Saturday, March 27, 2010

Coal Chute Rehab

I had planned on raking today but we were sidetracked with the coal chute door rehab. After much discussion (that is code for arguing), we (that is code for I persisted and won) decided to dig some more so we could get a small pot jack under the concrete.

R went to the barn to look for a pot jack and came back with a port-a-power which was just what we needed. A port-a-power is a portable hydraulic cylinder connected to little jack by a length of hydraulic hose.

After topping off the hydraulic cylinder with jack oil R placed the jack on a brick so it could not sink into the dirt. In the photo below, the jack is extended and under pressure.The next photo shows the cylinder. Notice the little lever on the cylinder on the opposite side of the cylinder where the hose is attached.
This lever has two positions, pump or release. You cannot build pressure when the lever is in the release position because this places the valve in the open position. Nothing will happen if you pump the handle while in this position because the fluid will just recirculate back to the reservoir. If you flip the lever to the pump position it will place the valve in the closed position. When you pump the handle while in the closed position the fluid cannot return to the reservoir so it builds hydraulic pressure in the hydraulic hose and pushes the jack upwards. This results in a mechanical advantage which is the relationship between the force you apply and the result you get. In layman's terms this is "big results for little effort."

A little bit of warning is needed here. Hydraulic pressure is serious business. If you are unsure of what you are doing it is best to pass up this method. Since both R and I are Journeyman trades people we are trained in the use of hydraulics. R has over 30 years of experience in hydraulics. When working with a partner always use voice commands when working with stored power. Before pumping the cylinder I always said, "hands clear" and I would not pump until R said he was "clear". The pounds per square inch would immediately crush and possibly shear off a finger before you could release the pressure.

Hydraulics works on what is called the Pascal's Law.

Pascal's Law

In fluid mechanics, the statement that a fluid at rest in a closed container, a pressure change in one part is transmitted without loss to every portion of the fluid and to the walls of the container. The principle was first stated by Blaise Pascal, who also discovered that the pressure at a point in a fluid at rest is the same in all directions, and that the pressure would be the same on all planes passing through a specific point.

Basically what he was saying is that the pressure is equal and undiminished throughout the system.

Hydraulic pressure is used to operate your vehicle's brakes. You push down on the brake pedal and that forces the piston in the master cylinder against the fluid in the cylinder. The pressure on the fluid in the master cylinder transmits through the lines to the brake cylinder at each wheel and forces the brake shoes or discs against the drums or rotor just like how the jack worked when I pumped the handle on the port-a-power.

This is why you need to maintain your brake fluid to the correct level. If your brake fluid level is low the resulting hydraulic pressure will be low and braking will be inefficient. Make sure you use the correct Dot rating of fluid (found in owners manual).

Brake fluid loses it's effectiveness when it becomes contaminated with moisture. DO NOT OPEN your brake fluid reservoir to check the level because this allows humidity to contaminate the brake fluid. You will notice that the brake reservoir is normally made of a light color plastic, this allows you to see the fluid level without opening the reservoir. If you cannot see the fluid line clearly take a flashlight and shine the light against the side of the reservoir. This should enable you to see the fluid level. The reservoir is marked with lines indicating operating and fill levels.

Brake fluids lose their effectiveness over time because of the high temperatures that they operate under. If your brake pads and discs are in good condition but your quality of braking is may need to replace your brake fluid. This should be left to a professional. Bleeding the brake lines of air can be a tricky procedure. Air in the brake lines will result in your brake pedal feeling mushy or even going all the way to the floor without your vehicle stopping. I know whenever they bleed the brakes on the race cars......much cursing and swearing can be heard. There's is nothing worse than being on the race track and having your brake pedal go to the floor!!!!

On to air pressure or pneumatic pressure. R decided to try the pneumatic orbital sander on the coal chute door before he hauled out the portable sand blaster.

Before using pneumatic tools add one or two drops of pneumatic oil into the fitting where you attach the compressed air line. The oil will lubricate the internal parts of your tool and help resist corrosion from the moisture that may get into your compressed air. You can reduce the chance of this happening if you install a filter/separator after your compressor but before your tool. Normally these are installed on permanent systems but today we were using the old and I mean OLD homemade portable compressor that R's dad made many moons ago.
The orbital sander worked surprisingly well. After he sanded he used the air gun to blow away the dirt that was on the concrete pad. Remember to wear eye protection when using an air gun. Dirt particles could get embedded in your eye if they are unprotected.
Here's the before photo of the coal chute.
And the after photo. R has a little more sanding to do before he primes and paints the coal chute.
We are very happy with the results.

Does anyone else have a coal chute?

FYI......If you are restoring an old house and need advice or guidance, hop on over to the Old House Web site. The site is very informative and is easily navigated. I personally love the forum area where readers can ask questions.