EECO Double Bearing Jack Units
Double bearing jack units consist of a single piston in a cylinder with a head bearing and packing gland at the upper end. An additional support bearing is located at a distance below the head bearing to allow the piston to carry an eccentric (off center) load. These jacks are normally used in applications that are not within the scope of ASME A17.1, however, EECO double bearing jack units are still designed in accordance with A17.1 guidelines.
Standard sizes for double bearing jack units are from 8.5” to 12.625” piston diameter. Other sizes are available.
Double bearing jack units are normally used for platform lift applications where the frame to which the jack unit is attached is not guided. A non-rotation device is generally installed, to prevent the platform from rotating.
Since EECO double bearing jack units are custom engineered, we request that you contact EECO Sales for available sizes and dimensions. Contact EECO Engineering for dimensions.
Pressure rating: Standard units are rated at 500 psi WP. Special high pressure units are available.
Designed for operating temperatures up to 150°F (65°C) maximum. Recommended operating temperature is 65° to 95°F (18° to 35°C).
All EECO jack units are designed and manufactured in accordance with ASME A17.1. Cylinders and pistons are manufactured from ASTM A 53, grade B, steel pipe, ERW or seamless as required; or from equivalent steel tubing. All steel parts are fabricated and machined from 60,000 psi tensile strength carbon steel. All welding is in accordance with the requirements of Part 8 of ASME A17.1-2002.
Designed for easy disassembly for repacking. An oil collection groove is provided and arrangement is included to connect an oil drain line to catch and reclaim oil that collects in the groove (it is necessary for the piston to carry a film of oil through the packing in order to provide smooth and quiet operation). The packing gland arrangement consists of a “pressure balanced” “U” type seal, a phenolic bearing and a wiper ring. Seals are designed for 150°F (65°C) maximum operating temperature. Recommended hydraulic fluid is 32 grade turbine oil, 150 SSU, or biodegradable vegetable oil may be used.
The upper end of the piston is fitted with a drilled and tapped plate, to receive a standard bolt for attachment to the platen plate (special mounting arrangements can be provided). The bottom of the piston is closed with a steel plate and is fitted with a stop ring to prevent the piston from leaving the cylinder. The piston is ground and polished to a surface finish of 16 to 20 micro-inches. Allowable variation in diameter after polishing is ± .015”. Multi-section pistons are joined with an internally threaded coupling, using Acme type thread for ease of assembly. All sections are assembled, sanded, and polished across the joints to ensure a matching surface.
Jack units manufactured for in-ground, or partial in-ground, installations are furnished with a safety bulkhead and seamless steel pipe cap at the bottom of the cylinder. Holeless units include a flat steel mounting plate, all in accordance with ASME A17.1. The upper end of the cylinder is arranged to accept the head bearing assembly. A bleeder plug is included to purge air from the jack unit. Standard pit supports are welded to the cylinder for mounting to pit channels when required (various designs can be provided to suit any requirement). A threaded or grooved oil line connection is provided. All cylinders are thoroughly cleaned, inspected, and tested for air leaks; and then painted with a heavy coat of an anti-corrosive material.
EECO offers three types of cylinder joints:
1. Threaded coupling (up through 16” cylinder OD).
2. Slip-fit (slide together coupling, no threads).
3. Butt-weld (with beveled ends for welding in field and “knock-off” pipe couplings for bolting the sections together during assembly and welding). EECO advises that all joints must be welded after assembly.
EECO can provide optional types of cylinder protection beyond the standard coating material, including: