DESC:Fully Powered Four Part Telescopic Boom with boom extension &retraction: - Synchronized sequential type using Hydraulic Cylinders only.

. Field of the invention
The present invention is generally related to a four part boom to be used in a crane, particularly in RT & Truck Mounted crane, wherein said four part boom assembly is provisioned with boom extension-retraction synchronized sequential type using hydraulic cylinders only (without any rope & chain).
Background
Usually three part boom assembly with synchronized boom extension/retraction is popular in cranes using one single stage cylinder & one set of extension/retraction rope or chain, or by using two single stage cylinders. In a conventional four part boom assembly, the fourth boom extension is a manual component which is manually extended / retracted or may be extended/retracted using rope or chain set.
Therefore the instant invention proposes a four part boom assembly to be used in a crane, wherein the fourth boom extension is so assembled with the third boom extension that it is not manually mounted on to the third boom extension and it is characterized in its automatic extension and retraction in the complete boom assembly with the help of one single stage cylinder & one double stage cylinder and wherein its extension/retraction is well synchronized & sequential type.
This complete boom assembly is not using any chain or rope set. This boom assembly is easy to assemble & its assembly is very easy in comparison to boom assembly using rope or chains. No. of components required for assembly of this boom are also less in no. in comparison to boom assembled using rope or chain.

Objective of the Invention
The main Objective of the present invention is a fully powered four part telescopic boom with boom extension &retraction synchronized sequential type using Hydraulic Cylinders only.
It is an another objective of the present invention wherein, a four part telescopic boom to be used in a crane, particularly in RT & Truck Mounted crane, wherein said four part boom assembly is provisioned with boom extension-retraction synchronized sequential type using hydraulic cylinders only without any rope & chain.
It is another objective of the present invention wherein, four part boom assembly comprises of a main boom (that is, mother boom), disposed with three boom extensions, namely 1st boom extension, 2nd boom extension and 3rd boom extension.
Yet another objective of the proposed invention is a four part boom assembly to be used in a crane, wherein the fourth boom extension is so assembled with the third boom extension that it is not manually mounted on to the third boom extension and it is characterized in its automatic extension and retraction in the complete boom assembly with the help of one single stage cylinder & one double stage cylinder and wherein its extension/retraction is well synchronized & sequential type.
Yet another objective of the present invention wherein, boom assembly is easy to assemble & its assembly is very easy in comparison to boom assembly using rope or chains.
Summary of the Invention
The present invention is generally related to a four part boom to be used in a crane, particularly in RT & Truck Mounted crane, wherein said four part boom assembly is provisioned with boom extension-retraction synchronized sequential type using hyd. cylinders only (without any rope & chain)
Said four part boom assembly comprises of a main boom (that is, mother boom), disposed with three boom extensions, namely 1stboom extension, 2ndboom extension and 3rdboom extension; wherein said boom assembly comprises following novel and characteristic constructional as well as functional features:
(i) 1st Boom extension is connected with mother boom by single stage cylinder. Rod is connected to mother boom & tube is connected to 1st Boom Extension.
(ii) 2nd& 3rdboom extension are connected with 1st boom extension by double stage telescopic cylinder. Tube of 1st stage of double stage cylinder is guided / supported with steel housing.
(iii) 1st stage tube of double stage cylinder is connected to 1st boom extension& 1st stage rod of double stage cylinder is connected to steel housing at one end & other end of steel housing is connected to 2nd boom extension.
(iv) 2nd stage rod of double acting cylinder is connected to 3rd boom extension.
(v) When operator actuates joystick, flow goes inside piston side of single stage cylinder. At the same time flow goes inside 1st stage tube / piston end of double acting cylinder through internal gallery in single stage cylinder. Hence 1st Boom extension starts opening w.r.t. mother boom & 2nd Boom extension starts opening w.r.t. 1st boom extension.
(vi) Hence synchronized operation of 1st& 2nd boom extension took place. At the same time rod end oil of single stage cylinder will pass to tank while rod end oil of 1st stage of double stage cylinder will be regenerated to bore end of double stage cylinder.
(vii) After synchronized extension of single stage cylinder and 1st stage of double stage cylinder, full oil will pass to 2nd extension stage of extension cylinder through 1st stage of cylinder. Hence 3rd Boom extension starts coming out.
(viii) Rod end oil of 2nd stage of double stage cylinder will be regenerated to bore end of 2nd stage of double stage cylinder.
(ix) Hence all Boom sections are come in extended condition. Operation of 1st& 2nd boom extension is synchronized w.r.t. mother boom & extension of 3rd boom extension is sequential.
(x) Now to retract boom again operator need to operate joystick in opposite direction. Before operating joystick in opposite direction, first operator need to energize DC valve fitted on single stage cylinder using toggle switch. This is to hold bore end oil of single stage cylinder. Hence no oil will come out from bore end of single stage cylinder.
(xi) Bore end oil of 2nd stage of extension cylinder will pass through Cindy valve of double stage cylinder to manifold block and then to tank through main control valve.
(xii) After sequential operation of 3rd boom extension, de-energize DC valve fitted on single stage cylinder using toggle switch. This is to pass bore end oil of 1st stage of double stage cylinder & single stage cylinder in synchronized manner through respective Cindy valves to manifold block and then to tank through main control valve (C.V.).
(xiii) Hence retraction of single stage cylinder and 1st stage of double stage cylinder is synchronized.
Brief Description of the Drawings
The present invention will be described in more detail hereinafter with the aid of the description which relates to preferred embodiments of the invention explained with reference to the accompanying schematic drawings, in which:
Figure 1 illustrates Schematic view of the elevation of complete boom assembly, showing how both the cylinders fixed with boom sections;
Figure 2 illustrates one schematic detailed view of rear portion of boom – General Boom Connections;
Figure 3 illustrates another schematic detail view of rear portion of Boom –General Boom Connections;
Figure 4 illustrates one schematic view of middle portion of Boom – General Boom Connections;
Figure 5 illustrates An Isometric view without main boom;
Figure 6 illustrates Isometric view without main boom & First Extension;
Figure 7 illustrates Isometric view only with jib head;
Figure 8 illustrates Isometric view only telescoping housing with cylinders;
Figure 9 illustrates one preferred embodiment of the HYDRAULIC SCHEMATIC;
Figure 10 illustrates Schematic plan of working of the hydraulic means (WORKING STEP - I));
Figure 11 illustrates Schematic plan of working of the hydraulic means (WORKING STEP - II);
Figure 12 illustrates Schematic plan of working of the hydraulic means (WORKING STEP - III);
Figure 13 illustrates Schematic plan of working of the hydraulic means (WORKING STEP - IV);
Figure 14 illustrates 2 STAGE TELESCOPE CYLINDER;
Detail Description of the Invention
The basic invention and the general field of the invention is described and illustrated herein below with certain schematic drawings and schematic scheme(s) associated with the construction and automatic synchronized sequential functioning of the proposed four part boom assembly.
Figure 1, 2, 3 and 4 shows various schematic views of the boom among which Figure 2 depicts a single stage cylinder that is fixed with main boom and its bore is fixed with first extension wherein TELE Cylinder’s 1st stage fixed with 1st extension Boom and Numeral 1 is Housing, connecting to 2nd Boom section only;
Figure 4 depicts one schematic view of middle portion of Boom i.e. General Boom Connections wherein, Jib head side view showing cylinders other side fixing with section that also show:
• Free End rollers of TELE Cylinder
• Free End rollers of single stage cylinder
• Anchoring of 1st stage of TELE cylinder with Numeral 1 housing, This Numeral 1 housing is connected with 2nd section of boom (As shown in another figure)
Anchoring of 2nd stage of TELE Cylinder with 3rd section of boom (Jib Head section).
Figure 9 shows one embodiment of Hydraulic Schematic; the working of various steps of this is explained in detail in Figure 10, 11, 12 and 13.
Figure 10 depicts Schematic plan of working of the hydraulic means (WORKING STEP - I)
Step-1:
• Extension of single stage cylinder & 1st stage of double stage cylinder is simultaneous;
• Rod end oil of single stage cylinder will pass to return Port ‘A’ of main control valve;
• Rod end oil of 1st stage of double stage cylinder is regenerated to bore end of same cylinder.
Figure 11depicts Schematic plan of working of the hydraulic means (WORKING STEP - II))
Step-2:
• After simultaneous extension of single stage cylinder and 1st stage of double stage cylinder, full oil will pass to 2nd extension stage of extension cylinder through 1st stage of cylinder;
• Rod end oil of 2nd stage of double stage cylinder will be regenerated to bore end of 2nd stage of double stage cylinder.
Figure 12 depicts Schematic plan of working of the hydraulic means (WORKING STEP - III)
Step-3:
(i) Energize DC valve fitted on single stage cylinder. This is to hold bore end oil of single stage cylinder;
(ii) No oil will come out from bore end of single stage cylinder;
(iii) Bore end oil of 2nd stage of extension cylinder will pass through Cindy valve of extension cylinder to manifold block and then to main control valve (C.V.).
Figure 13 depicts Schematic plan of working of the hydraulic means (WORKING STEP - IV)

Step-4:
• Simultaneous retraction of single stage cylinder and 1st stage of double stage cylinder;
• Bore end oil of single stage cylinder and 1st stage of double stage cylinder will pass through respective Cindy valves to manifold block and then to main control valve (C.V.).
Figure 14 depicts 2 STAGE TELESCOPE CYLINDER wherein such two stage telescopic cylinder is the essential part of the proposed four part boom assembly, mainly to assist in the function of automatic extension and retraction of said four part boom assembly.
In most preferred embodiment of the said four part telescopic boom assembly, the assembly of said two stage telescopic cylinder is characterized in:
• Very Long cylinder with each stage stroke of 7.7 meter.
• Said two stage cylinder is with integrated load holding valve – Cindy type which will help in precise control for extension/retraction of cylinder & this Cindy valve is leak free valve;
• Bore diameter of said cylinder is 140 mm (as outer) and 110mm (as inner);
• Rod Dia: 125mm and 90mm;
• Stroke: Each stage 7700 ± 5;
• Working pressure: 190 BAR;
• Test pressure: 250 BAR;
• Working temperature: -200C to +800C;
• Cylinder type: double acting;
• Cushioned type: Non-cushioned;
• Seal kit part No. DS11704.
Scope of the present invention:
Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore contemplated that such modifications can be made without departing from the spirit or scope of the present invention as defined.

CLAIMS:We Claim

1. A four part telescopic boom assembly to be used in a crane, particularly in RT & Truck Mounted crane, wherein said four part boom assembly is provisioned with boom extension-retraction synchronized sequential type using hydraulic cylinders only without any rope & chain.

2. A four part telescopic boom assembly, as claimed in claim 1, which comprises of a main boom (that is, mother boom), disposed with three boom extensions, namely 1st boom extension, 2nd boom extension and 3rd boom extension; wherein said boom assembly comprises following novel and characteristic constructional as well as functional features:
a) 1st Boom extension is connected with mother boom by single stage cylinder. Rod is connected to mother boom & tube is connected to 1st Boom Extension;
b) 2nd& 3rdboom extension are connected with 1st boom extension by double stage telescopic cylinder. Tube of 1st stage of double stage cylinder is guided / supported with steel housing;
c) 1st stage tube of double stage cylinder is connected to 1st boom extension& 1st stage rod of double stage cylinder is connected to steel housing at one end & other end of steel housing is connected to 2nd boom extension;
d) 2nd stage rod of double acting cylinder is connected to 3rd boom extension;
e) When operator actuates joystick, flow goes inside piston side of single stage cylinder. At the same time flow goes inside 1st stage tube / piston end of double acting cylinder through internal gallery in single stage cylinder. Hence 1st Boom extension starts opening w.r.t. mother boom & 2nd Boom extension starts opening w.r.t. 1st boom extension;
f) Hence synchronized operation of 1st& 2nd boom extension took place. At the same time rod end oil of single stage cylinder will pass to tank while rod end oil of 1st stage of double stage cylinder will be regenerated to bore end of double stage cylinder;
g) After synchronized extension of single stage cylinder and 1st stage of double stage cylinder, full oil will pass to 2nd extension stage of extension cylinder through 1st stage of cylinder. Hence 3rd Boom extension starts coming out;
h) Rod end oil of 2nd stage of double stage cylinder will be regenerated to bore end of 2nd stage of double stage cylinder;
i) Hence all Boom sections are come in extended condition. Operation of 1st& 2nd boom extension is synchronized w.r.t. mother boom & extension of 3rd boom extension is sequential;
j) To retract boom again, operator needs to operate joystick in opposite direction, wherein before operating joystick in opposite direction firstly the operator need to energize DC valve fitted on single stage cylinder using toggle switch, particularly with regard to hold bore end oil of single stage cylinder, and hence no oil will come out from bore end of single stage cylinder;
k) Bore end oil of 2nd stage of extension cylinder will pass through Cindy valve of double stage cylinder to manifold block and then to tank through main control valve;
l) After sequential operation of 3rd boom extension, de-energize DC valve fitted on single stage cylinder using toggle switch. This is to pass bore end oil of 1st stage of double stage cylinder & single stage cylinder in synchronized manner through respective Cindy valves to manifold block and then to tank through main control valve (C.V.); and
m) Hence retraction of single stage cylinder and 1st stage of double stage cylinder is synchronized.

3. A four part telescopic boom assembly, as claimed in claim 1 and 2, wherein said four part boom assembly is provisioned with boom extension-retraction synchronized sequential type using hydraulic cylinders only and without any rope & chain arrangement.

4. A four part telescopic boom assembly, as claimed in claim 1 and 2, wherein said fourth boom extension is so assembled with the third boom extension that it is not manually mounted on to the third boom extension and it is characterized in its automatic extension and retraction in the complete boom assembly with the help of one single stage cylinder & one double stage cylinder and wherein its extension/retraction is well synchronized & sequential type.

5. A four part telescopic boom assembly, as claimed in claim 1 and 2, wherein working of the hydraulic means towards extension/retraction of said four part telescopic boom assembly, at its first step (i.e. WORKING STEP - I) is as under:
Step-1:
• Extension of single stage cylinder & 1st stage of double stage cylinder is simultaneous;
• Rod end oil of single stage cylinder will pass to return Port ‘A’ of main control valve;
• Rod end oil of 1st stage of double stage cylinder is regenerated to bore end of same cylinder.

6. A four part telescopic boom assembly, as claimed in claim 1 and 2, wherein working of the hydraulic means towards extension/retraction of said four part telescopic boom assembly, at its second step (i.e. WORKING STEP - II) is as under:
Step-2:
• After simultaneous extension of single stage cylinder and 1st stage of double stage cylinder, full oil will pass to 2nd extension stage of extension cylinder through 1st stage of cylinder;
• Rod end oil of 2nd stage of double stage cylinder will be regenerated to bore end of 2nd stage of double stage cylinder.

7. A four part telescopic boom assembly, as claimed in claim 1 and 2, wherein working of the hydraulic means towards extension/retraction of said four part telescopic boom assembly, at its third step (i.e. WORKING STEP - III) is as under:
Step-3:
• Energize DC valve fitted on single stage cylinder, wherein this is to hold bore end oil of single stage cylinder;
• No oil will come out from bore end of single stage cylinder;
• Bore end oil of 2nd stage of extension cylinder will pass through Cindy valve of extension cylinder to manifold block and then to main control valve (C.V.).
8. A four part telescopic boom assembly, as claimed in claim 1 and 2, wherein working of the hydraulic means towards extension/retraction of said four part telescopic boom assembly, at its fourth step (i.e. WORKING STEP - IV) is as under:
Step-4:
• Simultaneous retraction of single stage cylinder and 1st stage of double stage cylinder;
• Bore end oil of single stage cylinder and 1st stage of double stage cylinder will pass through respective Cindy valves to manifold block and then to main control valve (C.V.).

9. A four part telescopic boom assembly, as claimed in claim 1, wherein the two stage telescope cylinder is provisioned particularly to carry out the automatic extension and retraction functions of said boom extensions.
10. A four part telescopic boom assembly, as claimed in claim 1, wherein in most preferred embodiment of the said four part telescopic boom assembly, the assembly of said two stage telescopic cylinder is characterized in:
• Very Long cylinder with each stage stroke of 7.7 meter.
• Said two stage cylinder is with integrated load holding valve – Cindy type which will help in precise control for extension/retraction of cylinder & this Cindy valve is leak free valve;
• Bore diameter of said cylinder is 140 mm (as outer) and 110mm (as inner);
• Rod Dia: 125mm and 90mm;
• Stroke: Each stage 7700 ± 5;
• Working pressure: 190 BAR;
• Test pressure: 250 BAR;
• Working temperature: -200C to +800C;
• Cylinder type: double acting;
• Cushioned type: Non-cushioned;
• Seal kit part No. DS11704