This system is a mobile, self-propelled, variable height, hydraulic lifting frame. It is primarily controlled from a remote, self contained power module, that is positioned away from the gantries. The gantries are designed to be operated on track.
GANTRY SYSTEM STRUCTURE...
A side shift mechanism allows to transverse the load giving the system the capacity to move the load in the 3 directions.
There are 4 jacking units, supported on wheels having one vertical lift cylinder and a vertical lift boom mounted on top. These units are self-propelled. The cylinders and booms of these jacking units are extended or retracted to lift or lower the load. The jacking units can move longitudinally to transport loads horizontally
- The lift cylinders are telescopic, multiple stage and double acting (pressure extend, pressure retract). They are designed to eliminate the use of troublesome hose reels. Double locking valves built into the lower base of the cylinders and are not subject to any hydraulic hose or tubing failures. An equalized pressure system is created by matching the load rating with maximum system pressure. This ensures that the cannot be overloaded. If a load is over the specified capacity, the system will simply not allow the gantry to lift the load.
- The lift telescopic boom is made of square steel tubing with solid steel bars attached on two sides. The heavy steel walls and boom overlap ensure that the lift cylinders will not be hindered by any side loading forces.
- The telescoping of the boom is driven by the lift cylinders.
- The steel booms protect the cylinders from side loading pressures (which cause them to leak, deteriorate and eventually fail), as well as protecting it from exterior damage to the chromed rods. Nylatron slider pads are fitted in the booms sections to ensure a tight fit and smooth operation avoiding steel on steel friction.
- The cam lock safety system automatically holds suspended loads indefinitely, when engaged with or without the assistance of lift cylinders. This is done mechanically with eccentric cam locks, cast of high strength steel alloy, that bite into the walls of the booms. This system allows gantries to be locked into place at any extended position, without leaving the lift cylinder pressurized. The cams are cast of high strength alloy steel and are automatically held open hydraulically when the gantry booms are being either raised or lowered. A coil spring engages the locks when the control lever is returned to neutral or if there is ever a loss of system pressure.
The beam header plate that firmly holds the lifting beam is mounted on a horizontal spherical bearing. This allows full 360 degrees rotation and side to side oscillation. If the lifting legs are at different heights or if the surface that is supporting the gantries is not perfectly level, the gantries will still firmly hold the lifting beams.
The control valving is pressure compensated with proportional controls for inching. This means that when the control levers are activated to the same position, the flow is equalized to each cylinder. Therefore the lifting beam will remain level when a load is unbalanced. The two speed system alerts the operator that the load is being applied to the gantry and at the same time reduces the speed at which the gantry extends.
The lift beam is a structural section, usually a wide flange rolled shape or a fabricated box section. This beam is placed on the header plates.
The cross beams, a second set of header beams, are placed across the first set and used to attach the load.The cross beams are needed because of the lifting arrangements of the installation reels
The cross beams sit on an hydraulic side shift system that allows the fine setting of the load on the transversal direction.
The lift links are structural fittings that are used to provide points of attachment between the header beams and the rigging attached to the load (wire rope slings, synthetic slings, etc.).
The planetary self propel system is integrally built into each housing and is operated from the control module. This allows the gantry to be propelled on a flat plate or simple channel track. This system can be easily disengaged to become free-wheeling for tip downs or load centring.
- The track is an assembly consisting of two parallel beams tied together at regular intervals. The beams are wide flange shapes fitted with one structural element that guide the jacking unit's wheels. The beam gage is equal to the transverse wheel spacing of the jacking unit wheel loads over significant clear span.
- Specially designed junction are provided to connect different sections of tracks.
- The tracks are normally laid on timber mats to increase the load spreading effect.
- The control module is the remote station that provides the energy that actuates the cylinders in the jacking units as well as the planetary propel system. The module incorporates an electric motor, gas, diesel or propane fuelled engine as the primary power source. All hydraulic valves and controls for all cylinders and the propel system are operated manually, without electro-hydraulic systems. The pressure compensated operator control valve will direct an equal amount of oil flow to each gantry, regardless of unequal load pressure, when the control levers are moved evenly. This feature makes all gantries lift and propel as equally as possible, regardless of loading. Each gantry has the capability to be individually controlled via one lever per gantry on the Control Module.
- On the control panel of the module load sensors/gauges provide the total weight being carried by each jacking unit. An extended wire connected to a digital screen inform the operator about the height of each of the 4 jacking units