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Electro Hydraulic Thrustor
Crane Control Equipments make Thrustor is a sturdy Electro Hydraulic device for exerting smooth controlled upward Thrust on any device with rated capacity from the beginning to the end of the full rated stroke.
These are provided with Clevis-Lug mounting, allowing them to be mounted up to ten degrees either way from the vertical.
All the Rubber surfaces are immersed in Oil, there by requiring very less maintenance.
One outstanding feature of our Thrustor is that any Mechanical Overloading cannot cause Overloading of the Electric Motor.
If the Load is greater than what the Thrustor can lift , the Piston will remain at the bottom of the Cylinder and the impeller will rotate harmlessly in Oil.
In the absence of Load the Piston stops at the end of the stroke and the Impeller rotates in the Oil as mentioned above.
Basically Crane Control Equipments make Electro Hydraulic Thrustor comprises of a Centrifugal Pump Impeller spinning in Oil there by developing a pressure head.
Since there is no outlet, delivery port as in case of a Pump, the pressure developed is impressed on the Piston which is directly coupled to the Load to be lifted. Thus a part of the pressure head is expanded in forming a kinetic head required to lift the Load.
The Centrifugal Pump Impeller is driven by an Electric Motor the capacity of which depends upon the capacity of the Thrustor .
For example in case of a 18 kg Thrustor the Motor is of 90 Watts, in case of 34 kg and 46 kg it is 150 Watts and in case of 68 kg and 114 Kg it is 220 Watts.
The major components of the Electro Hydraulic Thrustor are, a Cast Iron cylinder filled with Transformer Oil, a Aluminum Piston moving freely in it and a Drive Shaft down the center,through the Piston to the cylinder.
The Impeller draws Oil from above the Piston forcing the Oil beneath the Piston to give it an upward movement in the cylinder with pressure. The pressure is maintained whether the Piston is in motion or has come to a halt at the end of the intermediate position of the upward stroke.
The quantity of Transformer Oil required to be filled up in the Thrustor depends upon the capacity of the Thrustor. Recommended grade of Transformer Oil is BS 148 or equivalent.
The recommended quantities are:
Capacity of Thrustor
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Quantity of Oil
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18 Kg
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1.85 Ltrs.
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34 Kg
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2.50 Ltrs.
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46 Kg
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2.50 Ltrs.
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68 Kg
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4.25 Ltrs.
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114 Kg
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4.25 Ltrs.
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When the Thrustor Motor is de-energised, the Electro Hydraulic Thrustor drops from the lifted position, assisted by the Spring force provided for this purpose.
The Thrustor Motors are totally enclosed type and Stators are wound with class B insulation. These are designed for satisfactory operation at rated voltage of 415 Volts,3 Phase,50 Hz.
The allowable Voltage fluctuation is +- 5 %.
The power supply is given through Terminal Box fitted to the Thrustor which have provision for Conduit entry. The maximum cross section of Cable that can be accommodated is 2.5mm2.
The supply leads must be of flexible type so as to allow free movement to the Thrustor when operating.
INSTALLATION PROCEDURE OF THRUSTER
Mount the Thruster vertically and connect it by Pin joints to its load so that the side pressure which may cause jamming is avoided.
The Thruster when in operation should have complete freedom to pivot slightly. The Thrusters are supplied with out Oil.
A 3 Core supply cable is to be terminated on the Three Terminals inside the Terminal box. The Thruster Motor Windings are STAR connected with internal STAR point.
Any phase sequence is permitted for connection as the Thruster is designed for bi-directional working.
INSTALLATION PROCEDURE OF THRUSTER
Mount the Thruster vertically and connect it by Pin joints to its load so that the side pressure which may cause jamming is avoided.
The Thruster when in operation should have complete freedom to pivot slightly.
The Thrusters are supplied with out Oil.
Wipe away any dirt accumulated around the Oil Plug in the Tank cover.
Remove the Oil Plug and fill up Transformer Oil slowly as per the quantities mentioned above. Replace the Oil Plug and operate the Thruster several times.
You will observe that the Thruster will operate in a jerky and irregular manner due to fall in the Oil level. This is due to the Air trapped in the Cylinder . Remove the Oil Plug and top up the Oil level.
Repeat this procedure till the Thruster comes in smooth operation.
A 3 Core supply cable is to be terminated on the Three Terminals inside the Terminal box. The Thruster Motor Windings are STAR connected with internal STAR point.
Any phase sequence is permitted for connection as the Thruster is designed for bi-directional working.
PROCEDURE FOR MAINTENANCE OF THRUSTER
The Transformer Oil require changing every one year. How ever it is advisable to check the Oil level periodically as the level does come down due to evaporation.
At the time of replacing the Transformer Oil do not dismantle the Thruster as a Drain Plug is provided at the bottom of the Thruster.
Once the correct quantity of Oil is filled up repeat the procedure as mentioned above for smooth operation of the Thruster.
Electro-Hydraulic Thrusters (ST)
Electrical Supply
Unless otherwise specified, all thrusters are suitable for operation for 415 Volts,-Phase, 50 Hz powder supply. Thrusters for other voltage up to 600 VAC, 3-phase can be supplied against specifications.
Connection
The Thrusters operated equally well in both directions of rotation. Therefore, the three phase supply lines can be connected the Thrusters in any R-Y-B phase sequence. Provide adequate safety backups.
Oil Requirements
Thruster are supplied without oil to avoid spillage during transportation. They must be filled with sufficient quantity of oil before installation. For all models of thrusters, it is recommended to use Transformer Oil as specified in BS:148.
Installation Of Thrusters
All Thrusters are suitable for vertical mounting only. After filling the thruster with required quantity of oil, intall it by using the clevis and hinge pins provided. Insert the locking split pins.
Ensure that no exceesive transerse forces are acting on the thrust rod, Wipe out the dust, paint or oil deposits from the operating section of the thrust rod pins by dry and clean cloth.
Maintenance
The Thrusters is designed for long trouble free service. The motor winding are designed to meet contingencies, The bearings are adequately sized.
Routine maintenance schedule includes checking the oil levels and topping them it necessary. If oil contamination is detected, drain it out completely and refill with fresh oil. Check and correct.
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