FORM - 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
DEVICE FOR LEAK TESTING OF PROFILED APERTURES IN HOLLOW CAST METALLIC BODIES
Applicant:
MAHINDRA & MAHINDRA LIMITED
An Indian Company, GATEWAY BUILDING, APOLLO BUNDER, MUMBAI - 400001,
MAHARASHTRA, INDIA.
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

Field of the Invention
The present invention relates to device for leak testing of profiled apertures in hollow cast metallic bodies, particularly a mandrel for leak testing of bores and openings in crank cases, particularly a sealing mandrel for leak testing of crank bores and cam bore, idler bore and air inlet etc.
Background of the Invention
Generally, in order to save material, hollow castings are used for manufacturing large hollow cast metallic bodies, such as housings, crank cases. These hollow cast metallic bodies require a leak-proof chamber for accommodating engine oil without any oil leakage. Conventional leak-testing machines are employed for testing the leakage of oil from various profiled apertures, e.g. crank bores, cam bores. Normally, these leak testing machines are very complex and the testing process used is also a very time-consuming activity. Moreover, only skilled operator may align the crankcase with the sealing plugs. Bush pressing operations are conducted only on the crankcases found Ok after such leak-tests.
The bubble test is one of the oldest leak detection methods. In hollow cast metallic bodies, such as housings and crank cases having profiled apertures, e.g. crank bores and cam bores, are filled with pressurized air and then immersed under water. Wherever there is any leakage, air bubbles rise up. However, it is not possible to measure the rate of leakage directly and the air bubbles are required to be collected for measuring their volume and the rate of leakage can be determined after dividing this volume by the duration of measurement. The above process is predominantly a visual leak detection process, which is a crude process because the human eyes are prone to make errors. Even an experienced operator working with high concentration

may miss observing the bubbles. The sensitivity limit of the bubble test is also quite difficult to determine. The oil-passage leak testing machines are also quite large and heavy in size, which makes them very difficult to be transported to the leak testing machine manufacturer's plant for replacement of critically worn-out fixtures and sealing units.
Obviously, any such major maintenance would lead to the non-availability of such leak testing machine/s for conducting leak tests for at least a few months at the crankcase manufacturing plants of the manufacturer like Mahindra & Mahindra. Therefore, these oil-passage leak testing machines cannot be spared for periodic maintenance.
One of the available options is to entirely skip the leak test, however this process deviation is not recommended, because no machining process can ensure 100% quality of bores and skipping the leak detection test just because of non-availability of the leak testing machine may lead to immediate dissatisfaction or rejection at the next stage of assembly line.
Another option is by monitoring oil pressure at the time of engine testing, which is also prone to lapses on part of the testing personnel and thereby this may also lead to higher rejection after testing, which obviously could entail major scrap costs for the manufacturer.
Prior Art
DE10241368 (A1) discloses a method which involves joining the two housing parts at the sealing surfaces, sealing the opening and dividing plane relative to the surroundings, whereby the dividing plane sealing forms a second hollow volume around the dividing plane, filling the first and second hollow volumes with at least one first and a second pressure medium respectively,

applying a test pressure, continuously measuring the hollow volume pressure and detecting a variation. The method involves joining the two parts of the housing at the corresponding sealing surfaces, sealing the opening and dividing plane relative to the surroundings, whereby the dividing plane sealing forms a second hollow volume around the dividing plane, filling the first and second hollow volumes with at least one first and a second pressure medium respectively, applying a test pressure, continuously measuring a pressure in the hollow volume and detecting a pressure variation.
WO2014009785 (A2) discloses a leak test apparatus that tests for a leak in a workpiece includes a plate; a seal that is able to move relative to the plate and is supported by the plate; a driving portion that supports the plate and moves the plate; and a pressure chamber that is surrounded by the plate and the seal. The seal is formed in a shape that enables the pressure chamber to be communicated with an outside.
Disadvantages of the Conventional Leak Testing Machine
The conventional oil-passage leak detection machines have serious issues with the quality of the leak-test results obtained, and this necessitates a complete reconditioning of the machine. Due to the inconsistency observed during repeated leak-tests and the amount of time-consumed in this process and also because the leak detection test cannot be discontinued in the crankcases being manufactured, it was brainstormed by the inventors to find out ways for using the same leak testing machine with alternative cost-effective solutions until the machine is reconditioned or even replaced.
Prior art discusses very complex processes for leak detection. The proximity switches and sensors also fail frequently due to inadvertently getting dipped in water while conducting air-bubble tests. Therefore, there was a long-felt

need for providing a leak testing device for profiled apertures in the hollow cast metallic bodies, e.g. crankcases used in automotive industry and such other equipment. Although, the invention is described with reference to an oil-way leak test, the concept underlying the invention can easily be used for leak testing of water-way or other liquid passages.
Objects of the Invention
Some of the objects of the present invention - satisfied by at least one embodiment of the present invention - are as follows:
An object of the present invention is to provide a cost-effective device for leak testing machines for hollow cast metallic bodies, e.g. bores of crankcase.
Another object of the present invention is to provide a simple device for leak testing machines for hollow cast metallic bodies, e.g. bores of crankcase.
A further object of the present invention is to provide a device for leak testing of hollow cast metallic bodies, e.g. bores of crankcase, which device is easy to align on the bores of such hollow cast metallic bodies.
A still further object of the present invention is to provide a device for leak testing of hollow cast metallic bodies, e.g. bores of crankcase, which effectively work even in presence of water.
Yet another object of the present invention is to provide a device for leak testing of hollow cast metallic bodies, e.g. bores of crankcase, which can be configured for leak testing different number of hollow chambers.

These and other objects and advantages of the present invention will become more apparent from the following description, when read with the accompanying figures of drawing, which are however not intended to limit the scope of the present invention in any way.
Description of the Invention
Accordingly, a sealing mandrel in accordance with the present invention for leak testing of profiled apertures in hollow cast metallic bodies, e.g. crankcase is described in the following.
It should be understood that the embodiment described herein is merely a preferred embodiment of the present invention. The person skilled in the art may modify it according to the requirements for different hollow cast metallic bodies and according to the profiles of the apertures. All such modifications are to be considered within the spirit and ambit or scope of the present invention. Normally, a leak testing machine is used for leak testing of oil galleries in Crank and Cam bores. However, there is no standby equipment available for leakage testing in case of any emergency. For example, in a crankcase machining unit, the entire crank case machining line comes to standstill in case of the breakdown of the leak testing machine.
This solution proposed in accordance with the present invention is a cost-effective and reliable one and the standby unit ensures that the crankcase manufacturing line is not interrupted. This also facilitates periodic maintenance of the existing leak testing machine. Moreover, the sealing mandrel in accordance with the present invention requires no hydraulic or pneumatic activation. A single crank bore mandrel can be used for 2DI, 3DI & 4DI crankcases. Separate mandrels can be used for the cam bores.

Summary of the Invention
A device for leak-testing of profiled apertures in a hollow cast metallic body, wherein the device comprises:
a shaft supported at both ends in the profiled apertures provided in the hollow body;
a plurality of profiled outer sleeves tightly inserted over the shaft between the two side walls of the crank case;
a plurality of Teflon sleeves, each inserted over one of the profiled outer sleeves;
a cam-shaped front plate also locked on the shaft by means of a lock piece;
a front spacer to keep the front plate away from the outer sleeve at the handle end and an end sleeve to keep the lock pin in position in the profiled aperture;
a plurality of spacers disposed between two adjacent profiled outer sleeves;
a plurality of rubber seals disposed between the profiled outer sleeves and the Teflon sleeves; and
at least one fastener for tightening on the cam-shaped front plate.
Typically, one end of the shaft is supported by means of a lock pin and the other end of the shaft is supported by means of a handle locked in place by means of a lock piece on the shaft.

Typically, the device is a crank bore mandrel configured for leak-testing of crank bores in the crank case, the mandrel comprises:
an internal shaft supported at both ends in the crank bores in the crank case;
a plurality of flanged outer sleeves snug fitted over the internal shaft;
a plurality of Teflon sleeves, each inserted over one of the flanged outer sleeves;
a cam-shaped front plate;
a front spacer to keep the front plate away from the flanged sleeve at the handle end and an end sleeve to keep the lock pin in position in the crank bore;
a plurality of spacers, each disposed at the end away from the flanged end of the flanged sleeve;
a plurality of rubber sealing plugs, each disposed between the spacers and the Teflon sleeves; and
- at least one fastener for tightening on the cam-shaped front plate.
' Typically, one end of the internal shaft is supported and by means of a lock pin and centred in the crank bore and the other end of the shaft is supported and centred by means of a handle locked in place by a lock piece on the shaft.
Typically, the plurality of flanged outer sleeves are snug fitted over the shaft between the two side walls of the crank case and disposed at predetermined distance from each other according to configuration of the cam provided in the crank case.

Typically, the device is a cam bore mandrel configured for leak-testing of cam bores in the crank case, the mandrel comprises:
- an internal shaft is supported on one side of the crank case and the other end of the shaft supported and centred on the other side of the crank case;
- a cam-shaped front plate locked in place by means of the shaft lock piece on the shaft;
- at least two flanged sleeves snug fitted over the shaft and disposed at a predetermined distance from each other according to the type of cam Dl used in the crank case;
- at least two Teflon sleeves, each inserted over one of flanged sleeves;
- at least one first spacer, a second spacer and an end sleeve;
- at least two rubber sealing plugs; and
- at least one fastener for tightening on the cam-shaped front plate.
Typically, the internal shaft comprises one end thereof supported by a lock pin for centering it in the cam bore on one side of the crank case and the other end of the shaft supported on a handle locked in place by means of a shaft lock piece on the shaft and to be centred in another cam bore on the other side of the crank case.
Typically, the flanged sleeves are snug fitted over the shaft between the lock pin on one side of the shaft and the cam-shaped front plate locked on the other side of the shaft and the flanged sleeves adapted to be disposed at a predetermined distance from each other according to the type of cam Dl used in the crank case.

Typically, the first spacer keeps the cam-shaped front plate away from the outer sleeve at one end, the second spacer keeps the flanged outer sleeves at a predetermined distance from each other and the end sleeve keeps the shaft supported on the lock pin resting in a centred position in the crank bore at the other end.
Typically, the at least two rubber sealing plugs, one of which disposed between the flanged end of the first outer sleeve and the second spacer and the other rubber sealing plug disposed between the flanged end of the second outer sleeve and the end sleeve.
Typically, the device is a cam bore mandrel for leak-testing of cam bore in the crank case, the mandrel comprises:
- an internal shaft supported at both ends in the cam bores in the crank case, one end of the shaft is supported and by means of a lock pin and centred in the cam bore and the other end of the shaft is supported and centred by means of a handle locked in place by a lock piece on the shaft;
- a first flanged outer sleeve and a second flanged outer sleeve, both snug fitted over the shaft between the two side walls of the crank case and disposed at predetermined distance from each other according to configurations of the cam provided in the crank case;
- a first Teflon sleeve and a second Teflon sleeve, each inserted over the corresponding flanged outer sleeve;
- a cam-shaped front plate;
- a first spacer to keep the front plate away from the first flanged outer sleeve at the handle end and a second spacer to keep the second flanged outer sleeve from the first flanged outer sleeve;

- a front rubber seal disposed between the flange of the first flanged outer sleeve and an end rubber seal disposed between an end spacer which is supported on the lock piece and the flange of the second flanged outer sleeve; and
- at least one fastener for tightening on the cam-shaped front plate.
Typically, the device is a cam bore mandrel for leak-testing of cam bore in the crank case, the mandrel comprises:
- an internal shaft supported at both ends in the cam bores in the crank case, one end of the shaft is supported and by means of a lock pin and centred in the cam bore and the other end of the shaft is supported and centred by means of a handle locked in place by a lock piece on the shaft;
- a first flanged outer sleeve and a second flanged outer sleeve, both snug fitted over the shaft between the two side walls of the crank case and disposed at predetermined distance from each other according to configurations of the cam provided in the crank case;
- a first Teflon sleeve and a second Teflon sleeve, each inserted over the corresponding flanged outer sleeve;
- a cam-shaped front plate;
- a first spacer to keep the front plate away from the first flanged outer sleeve at the handle end and a second spacer to keep the second flanged outer sleeve from the first flanged outer sleeve;
- a front rubber seal disposed between the flange of the first flanged outer sleeve and an end rubber seal disposed between the lock pin and the flange of the second flanged outer sleeve; and
- at least one fastener for tightening on the cam-shaped front plate.

Brief Description of the Accompanying Drawings
The present invention will be briefly described with reference to the accompanying drawings, which include:
Figure 1A shows a crankcase with a threaded hole (not seen), which is closed by a conventional sealing plug;
Figure 1B shows a sealing plug for manually plugging an idler bore;
Figure 1C shows sealing plugs for manually plugging the oil galleries of air inlet;
Figure 2A shows a crank bore mandrel in accordance with the present invention for sealing the crank bores of a crankcase;
Figure 2B shows a crank bore mandrel sealing the crank bores of a crankcase;
Figure 3A shows a first embodiment (2DI) of the cam bore mandrel prepared in accordance with the present invention for sealing the cam bore of the crankcase;
Figure 3B shows a second embodiment (3DI) of the cam bore mandrel prepared in accordance with the present invention for sealing the cam bore of the crankcase;
Figure 3C shows a third embodiment (4DI) of the cam bore mandrel prepared in accordance with the present invention for sealing the cam bore of the crankcase;
Figure 4A shows a typical air inlet sealing arrangement in accordance with the present invention for the oil galleries;

Figure 4B shows a side view of an oil filter sealed with a typical air inlet sealing;
Figure 4C shows the components of the air inlet sealing arrangement shown in Figure 4B;
Figure 4D shows the components of the idler bore sealing arrangement shown in Figure 1B and 5C;
Figure 5A shows the top view of a crankcase fitted with the crank bore mandrel provided in accordance with the present invention for sealing the crank bore;
Figure 5B shows a perspective view of a crankcase fitted with the crank bore and cam bore mandrels provided in accordance with the present invention for sealing the crank and cam bores respectively;
Figure 5C shows the side view of a crankcase provided with an idler bore sealing in accordance with the present invention; and
Figure 6 shows the crank bore sealing mandrel being inserted by an operator from the left hand side of a crank case;
Detailed Description of the Accompanying Drawings
In the following, the sealing mandrel for leak testing of profiled apertures in hollow cast metallic bodies, e.g. crankcase in accordance with the present invention will now be described in more details with reference to the accompanying drawings without limiting the scope and ambit of the disclosure in any way.

Figure 1A shows a crankcase 10 provided with a threaded hole (not seen), which is closed by a conventional sealing plug 2.
Figure 1B shows an idler bore sealing plug 4 in accordance with the present invention for manual plugging to eliminate hydraulic cylinders in the machine.
Figure 1C shows sealing plug 6 for manually sealing the oil galleries of air inlet on the air-filter in order to eliminate the sealing done on the machine.
Figure 2A shows a crank bore mandrel common for 2DI, 3DI and 4DI models of the cam bore mandrel in accordance with the present invention for sealing the crank bores of a crankcase. It consists of an internal shaft 1A, a lock pin 1B, a handle 1C, a cam-shaped front plate 1D, a shaft lock piece 1E, one front spacer 1F, four black rubber sealing plugs 1G, four metallic flanged outer sleeves 1H, four red Teflon sleeves 11, four sealing plugs 1J, one end sleeve 1K, one set-up change piece 1L (not shown), two set-up change pieces 1M (not shown) and one M8x20 Allen screw. The assembled crank bore mandrel is assembled as shown in this figure. All the components described above except the rubber sealing plugs 1G and Teflon sleeves 11 are made of steel, e.g. EN-8. Here, sealing of all crank bores is achieved by providing sealing plugs U which are duly doweled at crank bore positions. The internal shaft 1A is inserted and tightened from the LHS end against the outer sleeve 1H to make these sealing plugs 1J expand in their place to seal the bores in the crankcase. Once, one of the bores is sealed, the other bores are restricted from expanding further on the applying air pressure in the crankcase.
Figure 2B shows a typical crank bore mandrel (also shown assembled on the crankcase as in Figure 2A) in accordance with the invention for sealing the crank bore of the crankcase.

Figure 3A shows a first embodiment (2DI) of the cam bore mandrel in accordance with the present invention for sealing the cam bore of the crankcase. This cam bore mandrel consists of a shaft 2A, a lock pin 2B, a handle 2C, a cam-shaped front plate 2D, a shaft lock piece 2E, one first spacer 2F, one front rubber sealing plug 2G, one first outer sleeve 2H, one first red Teflon sleeve 21, one second spacer 2J, one second sleeve 2K, another red outer Teflon sleeve 2L, one end rubber sealing plug 2M, and one end spacer 2N and one M8X20 Allen screw. The cam bore mandrel is assembled as shown in this figure.
All the components described above (except the rubber sealing plugs 2G and Teflon outer sleeves 21 and 2L) are made of steel, e.g. EN-8.
Figure 3B shows a second embodiment (3DI) of the cam bore mandrel prepared in accordance with the present invention. This cam bore mandrel consists of a shaft 3A, a lock pin 3B, a handle 3C, a cam-shaped front plate 3D, a shaft lock piece 3E, one first spacer 3F, one front rubber sealing plug 3G, one first smaller flanged sleeve 3H, one first red Teflon outer sleeve 31, one second spacer 3J, one middle rubber sealing plug 3K, one second longer flanged sleeve 3L, a second red Teflon outer sleeve 3M, one end spacer 3N, one end rubber sealing plug 3P, one end sleeve 3Q and one M8X20 Allen screw. The cam bore mandrel is assembled as shown in this figure. All the components described above (except the rubber sealing plugs 3G, 3K and 3P and Teflon outer sleeves 31 and 3M) are made of steel, e.g. EN-8.
Figure 3C shows a third embodiment (4DI) model of the cam bore mandrel prepared in accordance with the present invention. This cam bore mandrel consists of an internal shaft 4A, a lock pin 4B, a handle 4C, one cam-shaped front plate 4D, one shaft lock piece 4E, two spacers 4F, one front rubber seal 4G, one first flanged sleeve 4H, two red Teflon outer sleeves 41, 4P; one middle rubber seal 4J, one second flanged sleeve 4K, one end spacer 4L,

one end rubber seal 4M, one end sleeve 4N and one M8X20 Allen screw. The cam bore mandrel is assembled as shown in this figure. All the components described above (except the rubber sealing plugs 4G, 4J, 4M and Teflon outer sleeves 41, 4P) are made of steel, e.g. EN-8.
Figure 4A shows a typical air inlet sealing arrangement in accordance with the present invention for the oil galleries.
Figure 4B shows a side view of the crankcase fitted with an oil filter (encircled in Red) sealed with a typical air inlet sealing arrangement of Figure 4A.
Figure 4C shows the components of the air inlet sealing arrangement shown in Figures 4A and 4B. The air inlet sealing arrangement includes an air filling adaptor plate I and two locating pins III. Both the components are made of steel, preferably EN-8. Section A-A of the air filling adaptor plate I is also shown at II.
Figure 4D shows the components of the idler bore sealing arrangement shown in Figure 1B and 5C. Idler bore sealing plug includes two main oil gallery plugs I and one idler sealing adaptor II, these components are made of steel, preferably EN-8. One rubber seal III is also provided, which is preferably made of Nitrile rubber.
Figure 5A shows a view from top of a crankcase fitted with the crank bore mandrel in accordance with the present invention for sealing the crank bore.
Figure 5B shows a perspective view of crankcase fitted with the crank bore mandrel (Figure 3A) and the cam bore mandrel (Figures 3A to 3C) provided in accordance with the present invention for sealing the crank and cam bores respectively.

Figure 5C shows a side view of the crankcase provided with an idler bore sealing plug (Figure 1B) in accordance with the present invention.
Figure 6 shows the sealing crank bore mandrel being inserted by an operator into the crankcase from the left hand side for full tightening from the right hand side thereof.
Technical advantages and economic significance
Leak testing operation becomes quite easy and quick.
1. Alignment of crankcase with the sealing mandrels can be done even by a semi-skilled person.
2. Leak testing Machine can be spared for periodic maintenance due to available standby unit.
3. Under breakdown of the leak testing machine, leak tests are not required to be conducted under any deviation.
4. Precise Handling and positioning of crank case on fixture is not required.
5. "X","Y" & "Z "movement and aligning of the sealing plugs for crank and cam is not necessary.
6. Use of any proximity sensors is eliminated, thereby avoiding any complexities of the process due to sensors getting dipped in water.
Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", shall be understood to implies including a described element, integer or method step, or group of elements, integers or method steps, however, does not imply excluding any other element, integer or step, or group of elements, integers or method steps. The use of the expression "a", "at least" or "at least one" shall imply using one or more elements or ingredients or quantities, as used in the embodiment of the disclosure in order to achieve one or more of the intended objects or results of the present invention.

The exemplary embodiments described in this specification are intended merely to provide an understanding of various manners in which this embodiment may be used and to further enable the skilled person in the relevant art to practice this invention. The description provided herein is purely by way of example and illustration. The various features and advantageous details are explained with reference to this non-limiting embodiment in the above description in accordance with the present invention. The descriptions of well-known components and manufacturing and processing techniques are consciously omitted in this specification, so as not to unnecessarily obscure the specification.
Although the embodiments presented in this disclosure have been described in terms of its preferred embodiments, the skilled person in the art would readily recognize that these embodiments can be applied with modifications possible within the spirit and scope of the present invention as described in this specification. A person skilled in the art may make innumerable changes, variations, modifications, alterations and/or integrations in terms of materials and method used to configure, manufacture and assemble various constituents, components, subassemblies and assemblies, in terms of their size, shapes, orientations and interrelationships without departing from the scope and spirit of the present invention.
While considerable emphasis has been placed on the specific features of the preferred embodiment described here, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiments without departing from the principles of the invention. These and other changes in the preferred embodiment of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

We claim:
1. A device for leak-testing of profiled apertures in a hollow cast metallic
body, wherein the device comprises:
a shaft supported at both ends in the profiled apertures provided in said hollow body;
a plurality of profiled outer sleeves tightly inserted over said shaft between the two side walls of the crank case;
a plurality of Teflon sleeves, each inserted over one of said profiled outer sleeves;
a cam-shaped front plate also locked on said shaft by means of a lock piece;
a front spacer to keep said front plate away from said outer sleeve at the handle end and an end sleeve to keep the lock pin in position in the profiled aperture;
a plurality of spacers disposed between two adjacent profiled outer sleeves;
a plurality of rubber seals disposed between said profiled outer sleeves and said Teflon sleeves; and
at least one fastener for tightening on said cam-shaped front plate.
2. A device as claimed in claim 1, wherein one end of said shaft is
supported by means of a lock pin and the other end of said shaft is supported
by means of a handle locked in place by means of a lock piece on said shaft.

3. Device as claimed in claim 1, wherein said device is a crank bore
mandrel configured for leak-testing of crank bores in the crank case, said
mandrel comprises:
an internal shaft supported at both ends in the crank bores in the crank case;
a plurality of flanged outer sleeves snug fitted over said internal shaft;
a plurality of Teflon sleeves, each inserted over one of said flanged outer sleeves;
a cam-shaped front plate;
a front spacer to keep said front plate away from said flanged sleeve at the handle end and an end sleeve to keep the lock pin in position in the crank bore;
a plurality of spacers, each disposed at the end away from the flanged end of said flanged sleeve;
a plurality of rubber sealing plugs, each disposed between said spacers and said Teflon sleeves; and
- at least one fastener for tightening on said cam-shaped front plate.
4. Device as claimed in claim 3, wherein one end of said internal shaft is supported and by means of a lock pin and centred in the crank bore and the other end of said shaft is supported and centred by means of a handle locked in place by a lock piece on said shaft.
5. Device as claimed in claim 3, wherein said plurality of flanged outer sleeves are snug fitted over said shaft between the two side walls of the crank case and disposed at predetermined distance from each other according to configuration of the cam provided in the crank case.

6. Device as claimed in claim 1, wherein said device is a cam bore
mandrel configured for leak-testing of cam bores in the crank case, said
mandrel comprises:
- an internal shaft is supported on one side of said crank case and the other end of said shaft supported and centred on the other side of said crank case;
- a cam-shaped front plate locked in place by means of said shaft lock piece on said shaft;
- at least two flanged sleeves snug fitted over said shaft and disposed at a predetermined distance from each other according to the type of cam Dl used in the crank case;
- at least two Teflon sleeves, each inserted over one of flanged sleeves;
- at least one first spacer, a second spacer and an end sleeve;
- at least two rubber sealing plugs; and
- at least one fastener for tightening on said cam-shaped front plate. *

7. Device as claimed in claim 6, wherein said internal shaft comprises one end thereof supported by a lock pin for centering it in the cam bore on one side of said crank case and the other end of said shaft supported on a handle locked in place by means of a shaft lock piece on said shaft and to be centred in another cam bore on the other side of said crank case.
8. Device as claimed in claim 6, wherein said flanged sleeves are snug fitted over said shaft between said lock pin on one side of said shaft and said cam-shaped front plate locked on the other side of said shaft and said flanged sleeves adapted to be disposed at a predetermined distance from each other according to the type of cam Dl used in the crank case.

9. Device as claimed in claim 6, wherein said first spacer keeps said cam-shaped front plate away from said outer sleeve at one end, said second spacer keeps said flanged outer sleeves at a predetermined distance from each other and said end sleeve keeps said shaft supported on said lock pin resting in a centred position in the crank bore at the other end.
10. Device as claimed in claim 6, wherein said at least two rubber sealing plugs, one of which disposed between said flanged end of said first outer sleeve and said second spacer and the other rubber sealing plug disposed between the flanged end of said second outer sleeve and said end sleeve.
11. Device as claimed in claim 1, wherein said device is a cam bore mandrel for leak-testing of cam bore in the crank case, said mandrel comprises:

- an internal shaft supported at both ends in the cam bores in the crank case, one end of said shaft is supported and by means of a lock pin and centred in the cam bore and the other end of said shaft is supported and centred by means of a handle locked in place by a lock piece on said shaft;
- a first flanged outer sleeve and a second flanged outer sleeve, both snug fitted over said shaft between the two side walls of the crank case and disposed at predetermined distance from each other according to configurations of the cam provided in the crank case;
- a first Teflon sleeve and a second Teflon sleeve, each inserted over the corresponding flanged outer sleeve;
- a cam-shaped front plate;

- a first spacer to keep said front plate away from said first flanged outer sleeve at the handle end and a second spacer to keep said second flanged outer sleeve from said first flanged outer sleeve;
- a front rubber seal disposed between the flange of said first flanged outer sleeve and an end rubber seal disposed between an end spacer which is supported on said lock piece and the flange of said second flanged outer sleeve; and
- at least one fastener for tightening on said cam-shaped front plate.
12. Device as claimed in claim 1, wherein said device is a cam bore mandrel for leak-testing of cam bore in the crank case, said mandrel comprises:
- an internal shaft supported at both ends in the cam bores in the crank case, one end of said shaft is supported and by means of a lock pin and centred in the cam bore and the other end of said shaft is supported and centred by means of a handle locked in place by a lock piece on said shaft;
- a first flanged outer sleeve and a second flanged outer sleeve, both snug fitted over said shaft between the two side walls of the crank case and disposed at predetermined distance from each other according to configurations of the cam provided in the crank case;
- a first Teflon sleeve and a second Teflon sleeve, each inserted over the corresponding flanged outer sleeve;
- a cam-shaped front plate;
- a first spacer to keep said front plate away from said first flanged outer sleeve at the handle end and a second spacer to keep said second flanged outer sleeve from said first flanged outer sleeve;

- a front rubber seal disposed between the flange of said first flanged outer sleeve and an end rubber seal disposed between said lock pin and the flange of said second flanged outer sleeve; and
- at least one fastener for tightening on said cam-shaped front plate.