Two stage telescopic jack units (TJ series) consist of upper and lower pistons, a cylinder, and a head bearing and packing gland for each piston. The telescopic jack is a synchronous design where both pistons raise and lower at the same speed, at the same time. The lower piston is fitted with an additional packing gland at the lower end which rides against the internally honed cylinder.

Oil enters the jack at the bottom, below the packing gland on the lower piston. The annular (ring) area between the larger piston and the interior of the cylinder is the same as the area of the upper piston, so the upper piston moves the same distance as the lower piston when oil enters or leaves the jack (providing synchronous operation).

Telescopic jacks can be provided in one section only (no multi-section) and are designed for “guided” applications only where the frame to which the jack unit is attached is rigidly supported and guided. In some applications a guided stabilizer may be required on the upper head to meet code requirements. For in-ground applications, the stabilizer is guided by shoes that ride on the main guide rails, but for dual installations, auxiliary guide rails are required on both sides of the hatch (consult EECO Engineering).

Two stage telescopic jacks are available from 1.6” to 4.5” upper piston diameter, in a wide range of wall thicknesses.

Three stage telescopic jacks are available in a limited range of sizes (consult EECO).

Two stage telescopic jacks are designed for in-ground and holeless applications, cantilever or dual systems, and can be used on residential and roped systems.

For in-ground installations, the depth of the well hole required, as measured from the lower floor level is approximately collapsed jack length + under travel + depth of platform, bolster and platen + 1’-0”, as measured from the lower floor level.

For holeless installations, the total pit depth + distance from upper landing level to any overhead obstruction, must be approximately collapsed jack length + over travel + 1’-0” (overhead must be code compliant. If pit + overhead space is not sufficient, partial holes for the jacks can be provided.

Consult EECO Sales for for dimensional and application requirements for Three Stage Telescopic jacks.

For estimating purposes, the collapsed length of a two stage telescopic jack is approximately the total travel, including under travel (7” to 10”) and over travel (9” to 12”) divided by 2 + 2’-6”.

Pressure Rating for TJ series: 1200 psi max. WP.

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. EECO welding is CWB certified.

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:

1. Tapecoat (polyvinyl chloride tape), wrapped to a minimum of 20mm thickness, or more as required.

2. Special epoxy coating.

3. PVC pipe, sealed at the top by a special adapter ring, with inspection ports as required by ASME A17.1. PVC can be schedule 40 or schedule 80 and is furnished in the number of sections as required, with a pipe cap for sealing the lower end. EECO can also provide a leak monitoring system for the sealed PVC cylinder protection.