Foot Pedal Air Cylinder Installation

How to install a foot-pedal air cylinder that lifts the lid of a Glass Hive Furnace: tools needed, step-by-step installation, speed adjustment, troubleshooting and maintenance.

⬇ Download the printable PDF

Overview

The air cylinder stays extended at rest and retracts only while the foot pedal is held down. Releasing the pedal sends it back out.

The cylinder stands upright on a post beside the furnace, rod pointing up. A cable runs from the rod end up to a pulley on an arm at the top of the post, then across to the front corner of the furnace lid.

• Pedal up: the rod is extended (up), the cable is slack and the lid sits closed under its own weight.
• Pedal down: the rod retracts (down), pulls the cable over the pulley and lifts the lid open.
• Pedal released: the rod rises again and pays out cable, and the lid lowers closed under gravity at the speed the cylinder allows.

The cylinder only ever pulls the lid open. Gravity closes it, so closing force is the lid's own weight, not the cylinder's push.

Safety

• Lid drops when air is lost: if the compressor stops or a hose comes off while the lid is open, the lid's weight pulls the rod up and the lid falls shut. Never reach under or into an open lid.
• Startup surge: connecting air drives the rod up to full extension. If the lid was propped open, it will drop. Keep the lid closed and the area clear when hooking up.
• Heat: the cable crosses above the furnace, where hot air rises. Use steel wire rope and metal cable hardware, never synthetic rope. Keep the cylinder seals and polyurethane tubing (typically rated only about 140–175°F, 60–80°C) low on the post and away from the flue and hot shell.
• Pinch points: keep fingers out of the lid edge, the pulley, the cable and the rod's 20" travel. Use the pedal's guard so it can't be stepped on by accident.
• Post and pulley loads: the pulley carries up to about twice the cable tension, and the post sees that load at the top. Anchor the post solidly and use a pulley and arm rated well above the cylinder's pull.
• Working on it: close the lid, shut off and bleed the air before loosening any fitting or cable clamp.
• Pressure: use only enough pressure to lift the lid reliably, usually well under 80 psi. Lower pressure means less force if something gets caught. Never exceed the foot valve's rating of about 115 psi.

Tools and supplies

• Wrenches to fit the fittings (typically 14–22 mm, or adjustables)
• Tubing cutter or sharp utility knife, for clean square cuts
• Drill, bits and fasteners for the post, cylinder mount and lid eye
• Small screwdriver or hex key for the flow-control adjusters
• Soapy water in a spray bottle for leak checks
• Tape measure and marker
• Zip ties or tube clips to secure the tubing away from heat
• Heat shield material (sheet metal) if the cylinder or tubing sits near hot surfaces

Installation

1. Mount the post, cylinder and cable

1. Anchor the post beside the furnace so its top arm puts the pulley above and beside the lid. Brace it; it takes the full lifting load.
2. Bolt the cylinder to the lower part of the post with its rod pointing straight up and directly under the pulley. The cable must pull straight along the rod's line; a sideways pull wears the rod seal.
3. Mount the pulley on the arm, and the lifting eye on the lid's front corner.
4. Fit the rod-end eye or clevis to the rod (M16x1.5 thread).
5. Check the travel: the cylinder's 20" stroke takes in 20" of cable. Pull the cable 20" by hand with the lid in place and make sure the lid opens as far as you need without hitting the post or arm.
6. With the rod fully extended (up) and the lid closed, run the wire rope from the rod eye, over the pulley, to the lid eye. Clamp it with a little slack, about 1/2", so the lid seats fully and the rod isn't holding it up.
7. Keep the cylinder body and tubing low and out of the rising heat. Add a sheet-metal shield between the furnace and the post if needed.

2. Fit the cylinder

1. Remove any fittings that came installed in the cylinder ports.
2. Thread one 3/8" PT elbow flow control into each cylinder port. Use PTFE tape unless the threads have pre-applied sealant. Snug, don't overtighten.
3. Turn both flow controls about halfway closed for now.

3. Fit the foot valve

1. Thread the three 1/4" NPT push-to-connect fittings into ports P, A and B, with PTFE tape.
2. Thread the two mufflers into the exhaust ports (often on the underside or side, marked R and S or EA and EB).
3. Place the pedal on the floor where the operator stands, clear of the lid and hot glass. Secure it so it can't slide.

4. Find the outlet that has air at rest

1. Push a short piece of tubing into P and connect shop air at low pressure (about 30 psi). Don't touch the pedal.
2. Feel which outlet, A or B, is blowing. On most 4F210 valves it is B, but test to be sure.
3. Mark that port "EXTEND" and the other "RETRACT". Disconnect the air.

5. Run the tubing

1. Run tubing from the EXTEND port to the cylinder's back (cap-end) port, away from the rod.
2. Run tubing from the RETRACT port to the cylinder's front (rod-end) port, next to the rod.
3. Run the supply line from your shop air to P.
4. Cut tubing square and push it fully into each fitting, then tug to confirm it's locked.
5. Run the tubing down the post, away from hot surfaces and clear of the cable and lid, and clip it in place.

First startup and speed adjustment

Do the first test with the furnace cold, at low pressure, and with everyone clear of the lid.

1. Set the regulator to about 30 psi, with the lid closed.
2. Connect the air. The rod should rise to full extension and the lid stay closed. If the rod retracts and the lid lifts, swap the two tubes at the valve's A and B ports.
3. Press and hold the pedal: the lid should lift. Release it: the lid should lower closed.
4. If the lid won't lift at 30 psi, raise the pressure 10 psi at a time until it lifts smoothly. Stop there plus a small margin; extra pressure only adds force if something gets caught.
5. Spray soapy water on every fitting. Bubbles mean a leak; reseat the tubing or retighten the thread.
6. Adjust the speeds with the flow controls on the cylinder. Each one slows the air leaving its own port; turn in (clockwise) to slow down, out to speed up. The bottom (cap-end) port control sets how fast the lid lifts; the top (rod-end) port control sets how fast the lid lowers.
7. Set the lowering speed so the rod rises a bit slower than the lid would fall on its own. That keeps the cable taut and lets the lid down gently. If the rod rises faster, the cable goes slack, can jump off the pulley, and the lid drops hard onto the furnace.
8. Cycle it 10–20 times. Check that the cable tracks in the pulley groove, the clamps haven't slipped, and the post hasn't moved.
9. Bring the furnace up to temperature and check the cylinder, tubing, pulley and cable after an hour. If the cylinder or tubing is too hot to hold your hand on, add shielding or move them.

Troubleshooting

Maintenance

• Monthly: soapy-water leak check, and check mounting bolts and clevis pins for wear.
• Drain the compressor tank and any water trap regularly. Water in the line wears out the valve and cylinder seals.
• Wipe glass dust and grit off the cylinder rod so it doesn't damage the rod seal.
• Inspect tubing near the furnace for hardening, cracks or melting, and the wire rope for broken strands, kinks or heat damage. Replace either at the first sign.

⬇ Download the printable PDF

More customer resources

• Fuji PXR3 Controller Guide
• Kiln Control Box Wiring
• Element Coil Stretching
• All customer resources