Autoquip SERIES 35 SCISSORS LIFT - Manual (Page 30)

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6.3 General Maintenance
6.3.1 Hydraulic Cylinder Repair
6.3.1.1. Cylinder Plunger Removal
1. Raise lift to its full height and engage maintenance devices. See “Maintenance Devices”.
2. Disconnect electrical power to lift. Follow lock out-tag out procedure.
3. Disconnect cylinder hose at power unit end and insert into reservoir oil-fill hole.
4. Loosen the setscrew or hex bolt in the cylinder upper leg clevis (otherwise known as the Trunnion
clevis).
5. Remove the cylinder pin from the upper leg clevis.
6. Lift the cylinder out of the leg assembly.
7. Push the piston rod into the cylinder to eject as much oil as possible into a container.
6.3.1.2. Replace Cylinder Seals
1. Insert spanner wrench and turn upper bearing assembly clockwise until tip of retainer appears in slot.
Place a small screwdriver under retainer and turn retainer to remove.
2. Be sure hose port is open to allow air into cylinder. Pull piston rod out to remove upper bearing.
3. After all internal components have been removed, inspect inner walls of barrel. Use a cylinder hone to
remove any apparent nicks or scratches. Clean and flush barrel after honing.
4. Remove piston head nut from rod. Upper clevis and pin may be used to prevent rotation of rod while
loosening. Remove old piston.
5. Inspect groove for nicks or scratches that could affect seal or barrel walls; remove as necessary.
6. Install new piston, seals, and rod wiper.
7. Install and tighten piston head nut to 600-650 ft•lb of torque on 3½ inch bore cylinders or 850-950 ft•lb
on 4 inch bore cylinders. Upper clevis and pin may be used to prevent rotation of rod while tightening.
8. Liberally lubricate piston and seal with clean grease or oil.
9. Insert piston into barrel, taking care not to damage seal.
10.Slip bearing assembly into place and align retainer hole with slot in barrel.
11.Turn bearing with spanner wrench until retainer is reinserted completely.