Patent Publication Number: US-6659056-B2

Title: Valve train with a single camshaft

Description:
The present application is a continuation of International Application No. PCT/US01/03318 filed on Feb. 1, 2001. PCT/US01/03318 claims priority to U.S. application Ser. No. 09/494,856 filed Feb. 1, 2000, now U.S. Pat. No. 6,390,046. Applications PCT/US01/03318 and Ser. No. 09/494,856 are incorporated herein by reference. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     The present invention generally relates to an internal combustion engine including a plurality of cylinders, at least one intake valve per cylinder and at least one exhaust valve per cylinder. The present invention specifically relates to an internal combustion engine further including a valve train with a single camshaft operatively opening and closing the intake and exhaust valves. 
     BACKGROUND OF THE INVENTION 
     An internal combustion engine includes an engine block and a cylinder head. The engine block includes one or more cylinders, each cylinder having a piston movably disposed therein. The cylinder head is mounted upon the engine block to form a combustion chamber for each cylinder. The perimeter of a combustion chamber is defined by a bottom surface of the cylinder head, an upper portion of a cylinder, and a crown of the piston disposed within the cylinder. The cylinder head includes one or more intake passageways leading into the combustion chamber, and one or more exhaust passageways leading out of the combustion chamber. Each intake and exhaust passageway is constructed with a valve seat adjacent the combustion chamber and the construction includes a valve for cooperation with a corresponding valve seat. To obtain optimal engine performance, each combustion chamber is designed to be as compact as possible in view of the overall performance requirements for the engine and dimensional specifications for the engine block and the cylinder head. As such, the intake valve seats and the exhaust valve seats are typically arranged in close proximity with a bore disposed between the valves seats for either a spark plug or a fuel injector. 
     For an internal combustion engine which includes a valve train having dual overhead camshafts and associated cam followers mounted upon the cylinder head, the lateral width of the cylinder head must be sufficiently dimensioned to accommodate the dual camshafts, the cam followers, and either a spark plug or a fuel injector. However, the required lateral width for the cylinder head configured in this manner may exceed the dimensional specifications for the overall width of an engine, particularly if the engine is configured in a conventional “V” arrangement. Moreover, a close proximity arrangement of the intake valve seats and the exhaust valve seats normally necessitates an angular orientation of the valve heads of the intake valves and the exhaust valves toward a center longitudinal axis of the associated combustion chamber. As a result, the distance between the stem tops of the intake valves and the exhaust valves is expanded causing the distance between the two camshafts as mounted on the cylinder head to be expanded. Consequently, the lateral width of the cylinder head must be increased to support the two camshafts. This increase may cause the lateral width of an otherwise acceptable cylinder head to exceed the desired dimensional specifications. 
     Additionally, there are further disadvantages associated with a valve train having dual overhead camshafts and associated cam followers. First, any friction loss by the two camshafts and associated cam followers as the two camshafts are rotating may increase fuel consumption. Second, duel overhead camshafts and associated cam followers may not be economically feasible. Third, the minimization of manufacturing imperfections can be costly. Specifically, a cam follower has a planar or convex surface for engaging a cam of a camshaft. The cam follower is machined upon a rocker arm that is pivotally mounted onto the cylinder head and operatively mounted upon a valve. To achieve optimal engine performance, it is necessary that manufacturing imperfections are minimized for both the cam follower and the rocker arm. However, the overall cost for the valve train must be increased to attain a minimization of manufacturing imperfections. 
     Moreover, cylinder heads as known in the art for valve trains having dual overhead camshafts are not suitable for diesel engines. For each intake valve, known cylinder heads include a fluid intake passage extending from an intake port to an intake valve seat. Generally, the fluid intake passage has an arcuate configuration. As a result, air flowing into the intake port through the fluid intake passage will uniformly circulate along an open intake valve as the air enters into the corresponding combustion chamber. Consequently, the air tumbles within the combustion chamber. A tumbling of the air within the combustion chamber facilitates optimal engine performance for a gas engine. However, such tumbling would hinder optimal engine performance for a diesel engine. 
     In view of the foregoing issues, there is a need for minimizing the lateral width of a cylinder head while designing combustion chambers that are suitably compact to render optimal engine performance. There is also a need for improving upon valve trains having dual overhead camshafts, particularly for diesel engines. The present invention satisfies these needs in a novel and unobvious manner. 
     SUMMARY OF THE INVENTION 
     According to one embodiment of the present invention, a valve train with a single camshaft is disclosed. The single camshaft operatively opens and closes one or more intake valves and one or more exhaust valves. In one form of the present invention, a valve train is disclosed, comprising a cylinder head, one or more valves (intake or exhaust) movably positioned within the cylinder head, a crosshead pivotally adjoined to the cylinder head and operatively adjoined to each valve (intake or exhaust), a rocker arm pivotally adjoined to the cylinder head and operatively adjoined to the crosshead, and a camshaft rotatably adjoined to the cylinder head and operatively adjoined to the rocker arm. When the camshaft is rotated, the rocker arm and the crosshead pivot about the cylinder head to thereby move the valve(s) (intake or exhaust) within the cylinder head. 
     In a related embodiment of the present invention, a valve train is disclosed, comprising a cylinder head, one or more intake valves movably positioned within the cylinder head, one or more exhaust valves movably positioned within the cylinder head, an intake crosshead pivotally adjoined to the cylinder head and operatively adjoined to each intake valve, an exhaust crosshead pivotally adjoined to the cylinder head and operatively adjoined to each exhaust valve, an intake rocker arm pivotally adjoined to the cylinder head and operatively adjoined to the intake crosshead, an exhaust rocker arm pivotally adjoined to the cylinder head and operatively adjoined to the exhaust crosshead, and a camshaft rotatably adjoined to the cylinder head and operatively adjoined to both the intake rocker arm and exhaust rocker arm. When the camshaft is rotated, the intake rocker arm and the intake crosshead pivot about the cylinder head to thereby move the intake valve(s) within the cylinder head, and the exhaust rocker arm and the exhaust crosshead pivot about the cylinder head to thereby move the exhaust valve(s) within the cylinder head. 
     In yet another related embodiment of the present invention, a valve train is disclosed, comprising a cylinder head a valve train is disclosed, comprising a cylinder head including one ore more valve seats. The valve train further comprises a valve (intake or exhaust) removably seated within a corresponding valve seat, a crosshead pivotally adjoined to the cylinder head and operatively adjoined to the valves (intake or exhaust), a rocker arm pivotally adjoined to the cylinder head and operatively adjoined to the crosshead, and a camshaft rotatably adjoined to the cylinder head and operatively adjoined to the rocker arm. As the camshaft cyclically rotates, the rocker arm and the crosshead undulatedly pivot about the cylinder head to thereby undulatedly seat and unseat the valves (intake or exhaust) within the valve seat(s). 
     In yet another related embodiment of the present invention, a valve train is disclosed, comprising a cylinder head including one or more intake valve seats and one or more exhaust valve seats. The valve train further comprises an intake valve removably seated within a corresponding intake valve seat, an exhaust valve removably seated within a corresponding exhaust valve seat, an intake crosshead pivotally adjoined to the cylinder head and operatively adjoined to the intake valve(s), an exhaust crosshead pivotally adjoined to the cylinder head and operatively adjoined to the exhaust valve(s), an intake rocker arm pivotally adjoined to the cylinder head and operatively adjoined to the intake crosshead, an exhaust rocker arm pivotally adjoined to the cylinder head and operatively adjoined to the exhaust crosshead, and a camshaft rotatably adjoined to the cylinder head and operatively adjoined to both rocker arms. As the camshaft cyclically rotates, the intake rocker arm and the intake crosshead undulatedly pivot about the cylinder head to thereby undulatedly seat and unseat the intake valves within the intake valve seat(s), and the exhaust rocker arm and the exhaust crosshead undulatedly pivot about the cylinder head to thereby undulatedly seat and unseat the exhaust valve(s) within the exhaust valve seat(s). 
     One object of the present invention is to provide an improved valve train having a single camshaft arranged on a cylinder head to operatively open and close intake valves and/or exhaust valves. 
     Related objects and advantages of the present invention will be apparent from the following description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A is a diagrammatic top plan view of a first embodiment of a cylinder head in accordance with the present invention. 
     FIG. 1B is an enlarged, partial top plan view of the FIG. 1A cylinder head. 
     FIG. 1C is an enlarged, partial bottom plan view of the FIG. 1A cylinder head. 
     FIG. 2A is a diagrammatic top plan view of a second embodiment of a cylinder head in accordance with the present invention. 
     FIG. 2B is an enlarged, partial top plan view of the FIG. 2A cylinder head. 
     FIG. 2C is an enlarged, partial bottom plan view of the FIG. 2A cylinder head. 
     FIG. 3A is a diagrammatic top plan view of a third embodiment of a cylinder head in accordance with the present invention. 
     FIG. 3B is an enlarged, partial top plan view of the FIG. 3A cylinder head. 
     FIG. 3C is an enlarged, partial bottom plan view of the FIG. 3A cylinder head. 
     FIG. 4A is a diagrammatic top plan view of a fourth embodiment of a cylinder head in accordance with the present invention. 
     FIG. 4B is an enlarged, partial top plan view of the FIG. 4A cylinder head. 
     FIG. 4C is an enlarged, partial bottom plan view of the FIG. 4A cylinder head. 
     FIG. 5A is a top plan view of a first embodiment of a crosshead in accordance with the present invention. 
     FIG. 5B is a bottom plan view of the FIG. 5A crosshead. 
     FIG. 5C is a left side elevational view of the FIG. 5A crosshead. 
     FIG. 5D is a right side elevational view of the FIG. 5A crosshead. 
     FIG. 6A is a top plan view of a second embodiment of a crosshead in accordance with the present invention. 
     FIG. 6B is a bottom plan view of the FIG. 6A crosshead. 
     FIG. 6C is a left side elevational view of the FIG. 6A crosshead. 
     FIG. 6D is a right side elevational view of the FIG. 6A crosshead. 
     FIG. 7A is a top plan view of a third embodiment of a crosshead in accordance with the present invention. 
     FIG. 7B is a bottom plan view of the FIG. 7A crosshead. 
     FIG. 7C is a left side elevational view of the FIG. 7A crosshead. 
     FIG. 7D is a right side elevational view of the FIG. 7A crosshead. 
     FIG. 8A is a top plan view of a fourth embodiment of a crosshead in accordance with the present invention. 
     FIG. 8B is a bottom plan view of the FIG. 8A crosshead. 
     FIG. 8C is a left side elevational view of the FIG. 8A crosshead. 
     FIG. 8D is a right side elevational view of the FIG. 8A crosshead. 
     FIG. 9A is a top plan view of a fifth embodiment of a crosshead in accordance with the present invention. 
     FIG. 9B is a bottom plan view of the FIG. 9A crosshead. 
     FIG. 9C is a left side elevational view of the FIG. 9A crosshead. 
     FIG. 9D is a right side elevational view of the FIG. 9A crosshead. 
     FIG. 10A is a top plan view of a sixth embodiment of a crosshead in accordance with the present invention. 
     FIG. 10B is a bottom plan view of the FIG. 10A crosshead. 
     FIG. 10C is a left side elevational view of the FIG. 10A crosshead. 
     FIG. 10D is a right side elevational view of the FIG. 10A crosshead. 
     FIG. 11A is a top plan view of a first embodiment of a rocker arm in accordance with the present invention. 
     FIG. 11B is a right side elevational view of the FIG. 11A rocker arm. 
     FIG. 12A is a top plan view of a second embodiment of a rocker arm in accordance with the present invention. 
     FIG. 12B is a right side elevational view of the FIG. 12A rocker arm. 
     FIG. 13A is a diagrammatic top plan view of a first embodiment of a valve train in accordance with the present invention. 
     FIG. 13B is an enlarged, partial top plan view of the FIG. 13A valve train. 
     FIG. 13C is a front elevational view in full section of the FIG. 13A valve train. 
     FIG. 14A is a diagrammatic top plan view of a second embodiment of a valve train in accordance with the present invention. 
     FIG. 14B is an enlarged, partial top plan view of the FIG. 14A valve train. 
     FIG. 14C is a front elevational view in full section of the FIG. 14A valve train. 
     FIG. 15A is a diagrammatic top plan view of a third embodiment of a valve train in accordance with the present invention. 
     FIG. 15B is an enlarged, partial top plan view of the FIG. 15A valve train. 
     FIG. 15C is a front elevational view in full section of the FIG. 15A valve train. 
     FIG. 16A is a diagrammatic top plan view of a fourth embodiment of a valve train in accordance with the present invention. 
     FIG. 16B is an enlarged, partial top plan view of the FIG. 16A valve train. 
     FIG. 16C is a front elevational view in full section of the FIG. 16A valve train. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     For the purposes of promoting an understanding of the principles of the present invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the present invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the present invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the present invention relates. 
     The present invention relates to a valve train with a single camshaft. Additional primary components of the valve train include a cylinder head, one or more valves (intake and/or exhaust), one or more crossheads, and one or more rocker arms. For purposes of the present invention, the term adjoined as used herein is defined as a unitary fabrication, an affixation, a coupling, a mounting, an engagement, or an abutment of two or more components of the valve train. The valves are movably positioned within the cylinder head. Each crosshead is pivotally adjoined to the cylinder head and operatively adjoined to one or more valves. Each rocker arm is pivotally adjoined to the cylinder head and operatively adjoined to a crosshead. The camshaft is rotatably adjoined to the cylinder head and operatively adjoined to each rocker arm. A rotation of the camshaft pivots the rocker arm(s) and the crosshead(s) about the cylinder head causing the valves to move within the cylinder head. The present invention contemplates that each component of the valve train is made from a material or combination of materials as known in the art that are suitable for the operability of the valve train over an operative temperature range for an internal combustion engine. 
     The illustrated embodiments of a cylinder head, a crosshead, and a rocker arm are in accordance with the present invention and are therefore independently shown in FIGS. 1A-4C, FIGS. 5A-10C, and FIGS. 11A-12B, respectively. The illustrated embodiments of a valve and a cam shaft are in accordance with the known art, and are therefore shown in an assembled valve train of the present invention as shown in FIGS. 13A-16C. The present invention does not contemplate any limitations as to the geometric configurations and physical dimensions of any component of the valve train. Consequently, the illustrated embodiments of the primary components of the valve train are given solely for purposes of describing the best mode of the present invention, and are not meant to be limiting to the scope of the claims in any way. The illustrated embodiments of a cylinder head are intended to be mounted upon an engine block having six (6) cylinders with a pair of intake valves and a pair of exhaust valves per cylinder, and the illustrated embodiments of a crosshead are intended to be operatively adjoined to a pair of valves (intake or exhaust). However, it is to be appreciated and understood that a cylinder head in accordance with the present invention can be configured to be mounted upon an engine block having any number of cylinders with at least one intake valve per cylinder and at least one exhaust valve per cylinder. It is to be further appreciated and understood that a crosshead in accordance with the present invention can be operatively adjoined to one or more valves (intake or exhaust), and can be operatively adjoined to an intake valve and an exhaust valve. For the preferred embodiments of crossheads as illustrated herein, it is to be appreciated that each illustrated crosshead includes an arm for each valve operatively adjoined to the illustrated crosshead. Accordingly, the present invention contemplates decreasing or increasing the number of arms of an illustrated crosshead as a function of the number of valves to be operatively adjoined to the illustrated crosshead. 
     Referring to FIGS. 1A-1C, a first embodiment cylinder head  20  is shown. Cylinder head  20  includes a body  21 , and one or more combustion chamber covers  22 . Preferably, cylinder head  20  has six (6) combustion chamber covers  22  as shown. Combustion chamber covers  22  are recessed within and adjoined to a bottom surface  21   b  of body  21 . Preferably, body  21  and combustion chamber covers  22  are fabricated as a unitary member. Combustion chamber covers  22  are positioned along bottom surface  21   b  whereby each combustion chamber cover  22  will be vertically aligned with a corresponding cylinder of an engine block when body  21  is adjoined to the engine block to thereby define combustion chambers between combustion chamber covers  22 , the cylinders, and the pistons within the cylinders. Body  21  includes a pair of intake ports  23   a  and  23   b  for each combustion chamber cover  22 . Intake ports  23   a  and  23   b  are disposed within a left side surface  21   c  of body  21 . Left side surface  21   c  of body  21  is upwardly oriented to enhance fluid communication between intake ports  23   a  and  23   b  and an intake manifold (not shown) that is adjoined to body  21 . Body  21  further includes an exhaust port (not shown) for each combustion chamber cover  22 . The exhaust ports are disposed within a right side surface (not shown) of body  21 . 
     With continued reference to FIGS. 1B and 1C, each combustion chamber cover  22  includes a pair of intake valve seats  24   a  and  24   b , and a pair of exhaust valve seats  24   c  and  24   d . The intake valve seats  24   a  and  24   b  and the exhaust valve seats  24   c  and  24   d  are recessed within a bottom surface  22   a  of each combustion chamber cover  22 . Preferably, bottom surface  21   b  of body  21  and bottom surface  22   a  of combustion chamber covers  22  are planar and coplanar. For each combustion chamber cover  22 , body  21  includes an intake fluid passage  25   a  extending from intake port  23   a  to intake valve seat  24   a  and an intake fluid passage  25   b  extending from intake port  23   b  to intake valve seat  24   b . Alternatively, intake port  23   b  can be omitted from body  21  and intake fluid passages  25   a  and  25   b  can both extend from intake port  23   a  to intake valve seats  24   a  and  24   b , respectively. Also for each combustion chamber cover  22 , body  21  includes an exhaust fluid passage  25   c  extending from exhaust valve seat  24   c  to the corresponding exhaust port, and an exhaust fluid passage  25   d  extending from exhaust valve seat  24   d  to the corresponding exhaust port. Alternatively, for each combustion chamber cover  22 , body  21  can further include a second exhaust port disposed within the right side surface of body  21  with exhaust fluid passages  25   d  extending from exhaust valve seats  24   d  to the second exhaust ports. 
     Preferably, intake fluid passages  25   a  and  25   b  have curvilinear configurations with two opposing arcs therein to facilitate a swirling of air introduced into a corresponding combustion chamber. The curvilinear configuration intake fluid passage  25   a  is best illustrated in FIG.  13 C. Referring to FIG. 13C, a forward arc segment  25   e  of intake fluid passage  25   a  diagonally extends from intake port  23   a  in a substantially downward direction and then bends toward a substantially horizontal direction. A rearward arc segment  25   f  of intake fluid passage  25   a  extends from forward arc segment  25   e  in a substantially horizontal direction and then bends in a substantially downward direction toward intake valve seat  24   a . As a result, a substantial portion of any air flowing into intake port  23   a  through intake fluid passage  25   a  will circulate along a portion of an open intake valve  161   a  as the air enters into the corresponding combustion chamber. Consequently, the air swirls within the combustion chamber. To enhance the swirling of the air within the combustion chambers, intake valve seats  24   a  and  24   b  are positioned within combustion chamber covers  22  such that air entering the combustion chambers through intake valve seats  24   a  swirls in substantially the same direction as the air entering the combustion chambers through intake valve seats  24   b.    
     Referring again to FIGS. 1B and 1C, for each combustion chamber cover  22 , body  21  additionally includes a pair of intake bores  26   a  and  26   b  and a pair of exhaust bores  26   c  and  26   d  disposed therein. Each intake bore  26   a  extends from top surface  21   a  of body  21  to a corresponding intake fluid passage  25   a . Each intake bore  26   b  extends from top surface  21   a  of body  21  to a corresponding intake fluid passage  25   b . Each exhaust bore  26   c  extends from top surface  21   a  of body  21  to a corresponding exhaust fluid passage  25   c . Each exhaust bore  26   d  extends from top surface  21   a  of body  21  to a corresponding exhaust fluid passage  25   d . Body  21  also includes an intake lash adjuster seat  27   a , and an exhaust lash adjuster seat  27   b  for each combustion chamber cover  22 . Each intake lash adjuster seat  27   a  is disposed within top surface  21   a  of body  21  and is adjacent corresponding intake bores  26   a  and  26   b . For each combustion chamber cover  22 , intake bores  26   a  and  26   b  and intake lash adjuster seat  27   a  are positioned to support a mounting upon body  21  of an intake crosshead  70  of an intake valve assembly  160  as best illustrated in FIG.  13 B. Each exhaust lash adjuster seat  27   b  is disposed within top surface  21   b  of cylinder head  21  and is adjacent corresponding exhaust bores  26   c  and  26   d . For each combustion chamber cover  22 , exhaust bores  26   c  and  26   d  and exhaust lash adjuster seat  27   b  are positioned to support a mounting upon body  21  of an exhaust crosshead  70  of an exhaust valve assembly  170  as best illustrated in FIG.  13 B. Body  21  further includes a fuel injector bore  28   a  for each combustion chamber cover  22 , and combustion chamber covers  22  include a fuel injector bore  28   b  that is vertically aligned with a corresponding fuel injector bore  28   a.    
     Referring to FIGS. 2A-2C, a second embodiment cylinder head  30  is shown. Cylinder head  30  includes a body  31 , and one or more combustion chamber covers  32 . Preferably, cylinder head  30  has six (6) combustion chamber covers  32  as shown. Combustion chamber covers  32  are recessed within and adjoined to a bottom surface  31   b  of body  31 . Preferably, body  31  and combustion chamber covers  32  are fabricated as a unitary member. Combustion chamber covers  32  are positioned along bottom surface  31   b  whereby each combustion chamber cover  32  will be vertically aligned with a corresponding cylinder of an engine block when body  31  is adjoined to the engine block to thereby define combustion chambers between combustion chamber covers  32 , the cylinders, and the pistons within the cylinders. Body  31  includes a pair of intake ports  33   a  and  33   b  for each combustion chamber cover  32 . Intake ports  33   a  and  33   b  are disposed within a left side surface  31   c  of body  31 . Left side surface  31   c  of body  31  is upwardly oriented to enhance fluid communication between intake ports  33   a  and  33   b  and an intake manifold (not shown) that is adjoined to body  31 . Body  31  further includes an exhaust port (not shown) for each combustion chamber cover  32 . The exhaust ports are disposed within a right side surface (not shown) of body  31 . 
     With continued reference to FIGS. 2B and 2C, each combustion chamber cover  32  includes a pair of intake valve seats  34   a  and  34   b , and a pair of exhaust valve seats  34   c  and  34   d . The intake valve seats  34   a  and  34   b  and the exhaust valve seats  34   c  and  34   d  are recessed within a bottom surface  32   a  of each combustion chamber cover  32 . Preferably, bottom surface  31   b  of body  31  and bottom surfaces  32   a  of combustion chamber covers  32  are planar and coplanar. For each combustion chamber cover  32 , body  31  includes an intake fluid passage  35   a  extending from intake port  33   a  to intake valve seat  34   a  and an intake fluid passage  35   b  extending from intake port  33   b  to intake valve seat  34   b . Alternatively, intake port  33   b  can be omitted from body  31  and intake fluid passages  35   a  and  35   b  can both extend from intake port  33   a  to intake valve seats  34   a  and  34   b , respectively. Also for each combustion chamber cover  32 , body  31  includes an exhaust fluid passage  35   c  extending from exhaust valve seat  34   c  to the corresponding exhaust port, and an exhaust fluid passage  35   d  extending from exhaust valve seat  34   d  to the corresponding exhaust port. Alternatively, for each combustion chamber cover  32 , body  31  can further include a second exhaust port disposed within the right side surface of body  31  with exhaust fluid passages  35   d  extending from exhaust valve seats  34   d  to the second exhaust ports. 
     Preferably, intake fluid passages  35   a  and  35   b  have curvilinear configurations with two opposing arcs therein to facilitate a swirling of air introduced into a corresponding combustion chamber. The curvilinear configuration of intake fluid passage  35   b  is best illustrated in FIG.  14 C. Referring to FIG. 14C, a forward arc segment  35   e  of intake fluid passage  35   b  diagonally extends from intake port  33   b  in a substantially downward direction and then bends toward a substantially horizontal direction. A rearward arc segment  35   f  of intake fluid passage  35   b  extends from forward arc segment  35   e  in a substantially horizontal direction and then bends in a substantially downward direction toward intake valve seat  34   b . As a result, a substantial portion of any air flowing into intake port  33   b  through intake fluid passage  35   b  will circulate along a portion of an open intake valve  201   b  as the air enters into the corresponding combustion chamber. Consequently, the air swirls within the combustion chamber. To enhance the swirling of the air into the combustion chambers, intake valve seats  34   a  and  34   b  are positioned within combustion chamber covers  32  such that air entering the combustion chambers through intake valve seats  34   a  swirls in substantially the same direction as the air entering the combustion chambers through intake valve seats  34   b.    
     Referring again to FIGS. 2B and 2C, for each combustion chamber cover  32 , body  31  additionally includes a pair of intake bores  36   a  and  36   b  and a pair of exhaust bores  36   c  and  36   d  disposed therein. Each intake bore  36   a  extends from top surface  31   a  of body  31  to a corresponding intake fluid passage  35   a . Each intake bore  36   b  extends from top surface  31   a  of body  31  to a corresponding intake fluid passage  35   b . Each intake bore  36   c  extends from top surface  31   a  of body  31  to a corresponding exhaust fluid passage  35   c . Each intake bore  36   d  extends from top surface  31   a  of body  31  to a corresponding exhaust fluid passage  35   d . Body  31  also includes an intake lash adjuster seat  37   a , and an exhaust lash adjuster seat  37   b  for each combustion chamber cover  32 . Each intake lash adjuster seat  37   a  is disposed within top surface  31   a  of body  31  and is adjacent corresponding intake bores  36   a  and  36   b . For each combustion chamber cover  32 , intake bores  36   a  and  36   b  and intake lash adjuster seat  37   a  are positioned to support a mounting upon body  31  of an intake crosshead  90  of an intake valve assembly  200  as best illustrated in FIG.  14 B. Each exhaust lash adjuster seat  37   b  is disposed within top surface  31   b  of body  31  and is adjacent corresponding exhaust bores  36   c  and  36   d . For each combustion chamber cover  32 , exhaust bores  36   c  and  36   d  and exhaust lash adjuster seat  37   b  are positioned to support a mounting upon body  31  of an exhaust crosshead  90  of an exhaust valve assembly  210  as best illustrated in FIG.  14 B. Body  31  further includes a fuel injector bore  38   a  for each combustion chamber cover  32 , and combustion chamber covers  32  include a fuel injector bore  38   b  that is vertically aligned with a corresponding fuel injector bore  38   a.    
     Referring to FIGS. 3A-3C, a third embodiment cylinder head  40  is shown. Cylinder head  40  includes a body  41 , and one or more combustion chamber covers  42 . Preferably, cylinder head  40  has six (6) combustion chamber covers  42  as shown. Combustion chamber covers  42  are recessed within and adjoined to a bottom surface  41   b  of body  41 . Preferably, body  41  and combustion chamber covers  42  are fabricated as a unitary member. Combustion chamber covers  42  are positioned along bottom surface  41   b  whereby each combustion chamber cover  42  will be vertically aligned with a corresponding cylinder of an engine block when body  41  is adjoined to the engine block to thereby define combustion chambers between combustion chamber covers  42 , the cylinders, and the pistons within the cylinders. Body  41  includes a pair of intake ports  43   a  and  43   b  for each combustion chamber cover  42 . Intake ports  43   a  and  43   b  are disposed within a left side surface  41   c  of body  41 . Left side surface  41   c  of body  41  is upwardly oriented to enhance fluid communication between intake ports  43   a  and  43   b  and an intake manifold (not shown) that is adjoined to body  41 . Body  41  further includes an exhaust port (not shown) for each combustion chamber cover  42 . The exhaust ports are disposed within a right side surface (not shown) of body  41 . 
     With continued reference to FIGS. 3B and 3C, each combustion chamber cover  42  includes a pair of intake valve seats  44   a  and  44   b , and a pair of exhaust valve seats  44   c  and  44   d . The intake valve seats  44   a  and  44   b  and the exhaust valve seats  44   c  and  44   d  are recessed within a bottom surface  42   a  of each combustion chamber cover  42 . Preferably, bottom surface  41   b  of body  41  and bottom surfaces  42   a  of combustion chamber covers  42  are planar and coplanar. For each combustion chamber cover  42 , body  41  includes an intake fluid passage  45   a  extending from intake port  43   a  to intake valve seat  44   a  and an intake fluid passage  45   b  extending from intake port  43   b  to intake valve seat  44   b . Alternatively, intake port  43   b  can be omitted from body  41  and intake fluid passages  45   a  and  45   b  can both extend from intake port  43   a  to intake valve seats  44   a  and  44   b , respectively. Also for each combustion chamber cover  42 , body  41  includes an exhaust fluid passage  45   c  extending from exhaust valve seat  44   c  to the corresponding exhaust port, and an exhaust fluid passage  45   d  extending from exhaust valve seat  44   d  to the corresponding exhaust port. Alternatively, for each combustion chamber cover  42 , body  41  can further include a second exhaust port disposed within the right side surface of body  41  with exhaust fluid passages  45   d  extending from exhaust valve seats  44   d  to the second exhaust ports. 
     Preferably, intake fluid passages  45   a  and  45   b  have curvilinear configurations with two opposing arcs therein to facilitate a swirling of air introduced into a corresponding combustion chamber. The curvilinear configuration of intake fluid passage  45   b  is best illustrated in FIG.  15 C. Referring to FIG. 15C, a forward arc segment  45   e  of intake fluid passage  45   b  diagonally extends from intake port  43   b  in a substantially downward direction and then bends toward a substantially horizontal direction. A rearward arc segment  45   f  of intake fluid passage  45   b  extends from forward arc segment  45   e  in a substantially horizontal direction and then bends in a substantially downward direction toward intake valve seat  44   b . As a result, a substantial portion of any air flowing into intake port  43   b  through intake fluid passage  45   b  will circulate along a portion of an open intake valve  231   b  as the air enters into the corresponding combustion chamber. Consequently, the air swirls within the combustion chamber. To enhance the swirling of the air into the combustion chambers, intake valve seats  44   a  and  44   b  are positioned within combustion chamber covers  42  such that air entering the combustion chambers through intake valve seats  44   a  swirls in substantially the same direction as the air entering the combustion chambers through intake valve seats  44   b.    
     Referring again to FIGS. 3B and 3C, for each combustion chamber cover  42 , body  41  additionally includes a pair of intake bores  46   a  and  46   b  and a pair of exhaust bores  46   c  and  46   d  disposed therein. Each intake bore  46   a  extends from top surface  41   a  of body  41  to a corresponding intake fluid passage  45   a . Each intake bore  46   b  extends from top surface  41   a  of body  41  to a corresponding intake fluid passage  45   b . Each intake bore  46   c  extends from top surface  41   a  of body  41  to a corresponding exhaust fluid passage  45   c . Each intake bore  46   d  extends from top surface  41   a  of body  41  to a corresponding exhaust fluid passage  45   d . Body  41  also includes a pair of intake lash adjuster seats  47   a  and  47   b , and a pair of exhaust lash adjuster seats  47   c  and  47   d  for each combustion chamber cover  42 . Intake lash adjuster seats  47   a  and  47   b  are disposed within top surface  41   a  of body  41  and are adjacent corresponding intake bores  46   a  and  46   b . For each combustion chamber cover  42 , intake bores  46   a  and  46   b  and intake lash adjuster seats  47   a  and  47   b  are positioned to support a mounting upon body  41  of an intake crosshead  100  of an intake valve assembly  230  as best illustrated in FIG.  15 B. Exhaust lash adjuster seats  47   c  and  47   d  are disposed within top surface  41   b  of body  41  and are adjacent corresponding exhaust bores  46   c  and  46   d . For each combustion chamber cover  42 , exhaust bores  46   c  and  46   d  and exhaust lash adjuster seats  47   c  and  47   d  are positioned to support a mounting upon body  41  of an exhaust crosshead  100  of an exhaust valve assembly  240  as best illustrated in FIG.  15 B. Body  41  further includes a fuel injector bore  48   a  for each combustion chamber cover  42 , and combustion chamber covers  42  include a fuel injector bore  48   b  that is vertically aligned with a corresponding fuel injector bore  48   a.    
     Referring to FIGS. 4A-4C, a fourth embodiment cylinder head  50  is shown. Cylinder head  50  includes a body  51 , and one or more combustion chamber covers  52 . Preferably, cylinder head  50  has six (6) combustion chamber covers  52  as shown. Combustion chamber covers  52  are recessed within and adjoined to a bottom surface  51   b  of body  51 . Preferably, body  51  and combustion chamber covers  52  are fabricated as a unitary member. Combustion chamber covers  52  are positioned along bottom surface  51   b  whereby each combustion chamber cover  52  will be vertically aligned with a corresponding cylinder of an engine block when body  51  is adjoined to the engine block to thereby define combustion chambers between combustion chamber covers  52 , the cylinders, and the pistons within the cylinders. Body  51  includes a pair of intake ports  53   a  and  53   b  for each combustion chamber cover  52 . Intake ports  53   a  and  53   b  are disposed within a left side surface  51   c  of body  51 . Left side surface  51   c  of body  51  is upwardly oriented to enhance fluid communication between intake ports  53   a  and  53   b  and an intake manifold (not shown) that is adjoined to body  51 . Body  51  further includes an exhaust port (not shown) for each combustion chamber cover  52 . The exhaust ports are disposed within a right side surface (not shown) of body  51 . 
     With continued reference to FIGS. 4B and 4C, each combustion chamber cover  52  includes a pair of intake valve seats  54   a  and  54   b , and a pair of exhaust valve seats  54   c  and  54   d . The intake valve seats  54   a  and  54   b  and the exhaust valve seats  54   c  and  54   d  are recessed within a bottom surface  52   a  of each combustion chamber cover  52 . Preferably, bottom surface  51   b  of body  51  and bottom surfaces  52   a  of combustion chamber covers  52  are planar and coplanar. For each combustion chamber cover  52 , body  51  includes an intake fluid passage  55   a  extending from intake port  53   a  to intake valve seat  54   a  and an intake fluid passage  55   b  extending from intake port  53   b  to intake valve seat  54   b . Alternatively, intake port  53   b  can be omitted from body  51  and intake fluid passages  55   a  and  55   b  can both extend from intake port  53   a  to intake valve seats  54   a  and  54   b , respectively. Also for each combustion chamber cover  52 , body  51  includes an exhaust fluid passage  55   c  extending from exhaust valve seat  54   c  to the corresponding exhaust port, and an exhaust fluid passage  55   d  extending from exhaust valve seat  54   d  to the corresponding exhaust port. Alternatively, for each combustion chamber cover  52 , body  51  can further include a second exhaust port disposed within the right side surface of body  51  with exhaust fluid passages  55   d  extending from exhaust valve seats  54   d  to the second exhaust ports. 
     Preferably, intake fluid passages  55   a  and  55   b  have curvilinear configurations with two opposing arcs therein to facilitate a swirling of air introduced into a corresponding combustion chamber. The curvilinear configuration of intake fluid passage  55   a  is best illustrated in FIG.  16 C. Referring to FIG. 16C, a forward arc segment  55   e  of intake fluid passage  55   a  diagonally extends from intake port  53   a  in a substantially downward direction and then bends toward a substantially horizontal direction. A rearward arc segment  55   f  of intake fluid passage  55   a  extends from forward arc segment  55   e  in a substantially horizontal direction and then bends in a substantially downward direction toward intake valve seat  54   a . As a result, a substantial portion of any air flowing into intake port  53   a  through intake fluid passage  55   a  will circulate along a portion of an open intake valve  261   a  as the air enters into the corresponding combustion chamber. Consequently, the air swirls within the combustion chamber. To enhance the swirling of the air into the combustion chambers, intake valve seats  54   a  and  54   b  are positioned within combustion chamber covers  52  such that air entering the combustion chambers through intake valve seats  54   a  swirls in substantially the same direction as the air entering the combustion chambers through intake valve seats  54   b.    
     Referring again to FIGS. 4B and 4C, for each combustion chamber cover  52 , body  51  additionally includes a pair of intake bores  56   a  and  56   b  and a pair of exhaust bores  56   c  and  56   d  disposed therein. Each intake bore  56   a  extends from top surface  51   a  of body  51  to a corresponding intake fluid passage  55   a . Each intake bore  56   b  extends from top surface  51   a  of body  51  of to a corresponding intake fluid passage  55   b . Each intake bore  56   c  extends from top surface  51   a  of body  51  to a corresponding exhaust fluid passage  55   c . Each intake bore  56   d  extends from top surface  51   a  of body  51  to a corresponding exhaust fluid passage  55   d . Body  51  also includes a pair of intake lash adjuster seats  57   a  and  57   b , and a pair of exhaust lash adjuster seats  57   c  and  57   d  for each combustion chamber cover  52 . Intake lash adjuster seats  57   a  and  57   b  are disposed within top surface  51   a  of body  51  and are adjacent corresponding intake bores  56   a  and  56   b . For each combustion chamber cover  52 , intake bores  56   a  and  56   b  and intake lash adjuster seats  57   a  and  57   b  are positioned to support a mounting upon body  51  of an intake crosshead  110  of an intake valve assembly  260  as best illustrated in FIG.  16 B. Exhaust lash adjuster seats  57   c  and  57   d  are disposed within top surface  51   a  of body  51  and are adjacent corresponding exhaust bores  56   c  and  56   d . For each combustion chamber cover  52 , exhaust bores  56   c  and  56   d  and exhaust lash adjuster seats  57   c  and  57   d  are positioned to support a mounting upon body  51  of an exhaust crosshead  110  of an exhaust valve assembly  270  as best illustrated in FIG.  16 B. Body  51  further includes a fuel injector bore  58   a  for each combustion chamber cover  52 , and combustion chamber covers  52  include a fuel injector bore  58   b  that is vertically aligned with a corresponding fuel injector bore  58   a.    
     Referring to FIGS. 5A-5D, a first embodiment crosshead  60  is shown. Crosshead  60  comprises a body  61 , a head  62  adjoined to body  61 , an arm  63  adjoined to body  61 , and an arm  64  adjoined to body  61 . Preferably, body  61 , head  62 , arm  63 , and arm  64  are fabricated as an unitary member. A generally hemispherical surface  62   a  of head  62  extends from a planar surface  61   a  of body  61 . A planar surface  62   b  of head  62  extends from and is coplanar with a planar surface  61   b  of body  61 . Head  62  has a generally hemispherical indentation  62   c  disposed within surface  62   b . A planar surface  63   a  of arm  63  is separated from surface  61   a  by a sidewall  63   d . A planar surface  63   b  of arm  63  extends from and is coplanar with surface  61   b . Arm  63  includes a convex slot  63   c  disposed within surface  63   b . A planar surface  64   a  of arm  64  is separated from surface  61   a  by sidewall  64   d . A planar surface  64   b  of arm  64  extends from and is coplanar with surface  61   b . Arm  64  includes a convex slot  64   c  disposed within surface  64   b . Surfaces  61   a ,  61   b ,  62   b ,  63   a ,  63   b ,  64   a , and  64   b  are substantially parallel. Crosshead  60  is designed to be mounted upon cylinder head  20  (FIGS. 1A through 1C) and the like. Thus, as shown in FIG. 5A, a left side portion and a right side portion of body  61  are asymmetrically configured and dimensioned relative to a longitudinal axis  65  centered between arms  63  and  64 . 
     Referring to FIGS. 6A-6D, a second embodiment crosshead  70  is shown. Crosshead  70  comprises a body  71 , a head  72  adjoined to body  71 , an arm  73  adjoined to body  71 , and an arm  74  adjoined to body  71 . Preferably, body  71 , head  72 , arm  73 , and arm  74  are fabricated as a unitary member. A planar and curved surface  72   a  of head  72  extends from surface  71   a  of body  71 . A planar surface  72   b  of head  72  is separated from surface  71   b  of body  71  by a side wall  72   d . Head  72  has a generally hemispherical indentation  72   c  disposed within surface  72   b . A planar surface  73   a  of arm  73  extends from surface  71   a . A planar surface  73   b  of arm  73  is separated from surface  71   b  by a side wall  73   d . Arm  73  includes a convex slot  73   c  disposed within surface  73   b . A planar surface  74   a  of arm  74  extends from surface  71   a . A planar surface  74   b  of arm  74  is separated from surface  71   b  by a side wall  74   d . Arm  74  includes a convex slot  74   c  disposed within surface  74   b . Surfaces  71   a ,  71   b ,  72   a ,  72   b ,  73   a ,  73   b ,  74   a , and  74   b  are substantially parallel. Surfaces  72   b ,  73   b , and  74   b  are substantially coplanar. Crosshead  70  is designed to be mounted upon cylinder head  20  (FIGS. 1A through 1C) and the like. Thus, as shown in FIG. 6A, a left side portion and a right side portion of body  71  are asymmetrically configured and dimensioned relative to a longitudinal axis  75  centered between arms  73  and  74 . 
     Referring to FIGS. 7A-7D, a third embodiment crosshead  80  is shown. Crosshead  80  comprises a body  81 , a head  82  adjoined to body  81 , an arm  83  adjoined to body  81 , and an arm  84  adjoined to body  81 . Preferably, body  81 , head  82 , arm  83 , and arm  84  are fabricated as a unitary member. A generally hemispherical surface  82   a  of head  82  extends from a planar surface  81   a  of body  81 . A planar surface  82   b  of head  82  extends from a planar surface  81   b  of body  81 . Head  82  has a generally hemispherical indentation  82   c  disposed within surface  82   b . A planar surface  83   a  of arm  83  angularly extends from surface  81   a . A generally convex surface  83   b  of arm  83  extends from surface  81   b . Arm  83  includes a generally convex slot  83   c  disposed within surface  83   b . A planar surface  84   a  of arm  84  angularly extends from surface  81   a . Surface  81   a  is inclined from surface  82   a  to surfaces  83   a  and  84   a . A generally convex surface  84   b  of arm  84  extends from surface  81   b . Arm  84  includes a generally convex slot  84   c  disposed within surface  84   b . Crosshead  80  is designed to be mounted upon cylinder head  20  (FIGS. 1A through 1C) and the like. Thus, as shown in FIG. 7A, a left side portion and a right side portion of body  81  are asymmetrically configured and dimensioned relative to a longitudinal axis  85  centered between arms  83  and  84 . 
     Referring to FIGS. 8A-8D, a fourth embodiment crosshead  90  is shown. Crosshead  90  comprises a body  91 , a head  92  adjoined to body  91 , an arm  93  adjoined to body  91 , and an arm  94  adjoined to body  91 . Preferably, body  91 , head  92 , arm  93 , and arm  94  are fabricated as a unitary member. A planar surface  92   a  of head  92  downwardly extends from a planar surface  91   a  of body  91 . A planar surface  92   b  of head  92  downwardly extends from a planar surface  91   b  of body  91 . Head  92  has a generally hemispherical indentation  92   c  disposed within planar surface  92   b . A planar surface  93   a  of arm  93  extends from surface  91   a  of body  91 . A generally convex surface  93   b  of arm  93  extends from surface  91   b . Arm  93  includes a generally convex slot  93   c  disposed within surface  93   b . A planar surface  94   a  of arm  94  extends from surface  91   a  of body  91 . A generally convex surface  94   b  of arm  94  extends from surface  91   b  of body  91 . Arm  94  includes a generally convex slot  94   c  disposed within surface  94   b . Surfaces  91   a ,  91   b ,  93   a , and  94   a  are substantially parallel. Surfaces  91   a ,  93   a , and  94   a  are substantially coplanar. Crosshead  90  is designed to be mounted upon cylinder head  30  (FIGS. 2A through 2C) and the like. Thus, as shown in FIG. 8A, a left side portion and a right side portion of body  91  are symmetrically configured and dimensioned relative to a longitudinal axis  95  centered between arms  93  and  94 . 
     Referring to FIGS. 9A-9D, a fifth embodiment crosshead  100  is shown. Crosshead  100  comprises a body  101 , a head  102  adjoined to body  101 , a head  103  adjoined to body  101 , an arm  104  adjoined to body  101 , and an arm  105  adjoined body  101 . Preferably, body  101 , head  102 , head  103 , arm  104 , and arm  105  are fabricated as an unitary member. A planar surface  102   a  of head  102  downwardly extends from a planar surface  101   a  of body  101 . A planar surface  102   b  of head  102  downwardly extends from a planar surface  101   b  of body  101 . Head  102  has a generally hemispherical indentation  102   c  disposed within surface  102   b . A planar surface  103   a  of head  103  downwardly extends from planar surface  101   a  of body  101 . A planar surface  103   b  of head  103  downwardly extends from planar surface  101   b  of body  101 . Head  103  has a generally hemispherical indentation  103   c  disposed within surface  103   b . A planar surface  104   a  of arm  104  extends from surface  101   a  of body  101 . A generally convex surface  104   b  of arm  104  extends from surface  101   b  of body  101 . Arm  104  includes a generally convex slot  104   c  disposed within surface  104   b . A planar surface  105   a  of arm  105  extends from surface  101   a  of body  101 . A generally convex surface  105   b  of arm  105  extends from surface  101   b  of body  101 . Arm  105  includes a generally convex slot  105   c  disposed within surface  105   b . Surfaces  101   a ,  101   b ,  104   a , and  105   a  are substantially parallel. Surfaces  101   a ,  104   a , and  105   a  are substantially coplanar. Crosshead  100  is designed to be mounted upon cylinder head  40  (FIGS. 3A through 3C) and the like. Thus, as shown in FIG. 9A, a left side portion and a right side portion of body  101  are symmetrically configured and dimensioned relative to a longitudinal axis  106  centered between arms  103  and  104 . 
     Referring to FIGS. 10A-10D, a sixth embodiment crosshead  110  is shown. Crosshead  110  comprises a body  111 , a head  112  adjoined to body  111 , a head  113  adjoined to body  111 , an arm  114  adjoined to body  111 , and an arm  115  adjoined to body  111 . Preferably, body  111 , head  112 , head  113 , arm  114 , and arm  115  are fabricated as an unitary member. A planar surface  112   a  of head  112  downwardly extends from a planar surface  111   a  of body  111 . A planar surface  112   b  of head  112  downwardly extends from a planar surface  111   b  of body  111 . Head  112  has a generally hemispherical indentation  112   c  disposed within surface  112   b . A planar surface  113   a  of head  113  downwardly extends from a planar surface  111   a  of body  111 . A planar surface  113   b  of head  113  downwardly extends from a planar surface  111   b  of body  111 . Head  113  has a generally hemispherical indentation  113   c  disposed within surface  113   b . A planar surface  114   a  of arm  114  extends from surface  111   a  of body  111 . A generally convex surface  114   b  of arm  114  extends from surface  111   b  of body  111 . Arm  114  includes a generally convex slot  114   c  disposed within surface  114   b . A planar surface  115   a  of arm  115  extends from surface  111   a  of body  111 . A generally convex surface  115   b  of arm  115  extends from surface  111   b  of body  111 . Arm  115  includes a generally convex slot  115   c  disposed within surface  115   b . Surfaces  111   a ,  111   b ,  114   a , and  115   a  are substantially parallel. Surfaces  111   a ,  114   a , and  115   a  are substantially coplanar. Crosshead  110  is designed to be mounted upon cylinder head  50  (FIGS. 4A through 4C) and the like. Thus, as shown in FIG. 10A, a left side portion and a right side portion of body  111  are asymmetrically configured and dimensioned relative to a longitudinal axis  116  centered between arms  113  and  114 . 
     Referring to FIGS. 11A and 11B, a first embodiment rocker arm  120  is shown. Rocker arm  120  comprises a body  121 , an elephant foot  122 , a casing  123 , and a wheel  124 . Elephant foot  122  is adjoined to (preferably affixed to) a bottom surface of a distal end  121   a  of body  121 . Casing  123  is movably adjoined to (preferably movably engaged with) elephant foot  122 . Casing  123  can be positioned in various angular orientations relative to elephant foot  122 . Wheel  124  is inserted within a slot  121   c  disposed in an upper portion of a proximal end  121   b  of body  121 , and is rotatably adjoined with (preferably detachably coupled to) end  121   b  by a pin  124   a . A generally cylindrical aperture  121   d  extends through a lower portion of proximal end  121   b  of body  121 . Aperture  121   d  is spaced from slot  121   c.    
     Referring to FIGS. 12A and 12B, a second embodiment rocker arm  130  is shown. Rocker arm  130  comprises a body  131 , a lash adjuster  132 , and a wheel  133 . Lash adjuster  132  is disposed within a bottom surface (not shown) of a distal end  131   a  of body  131  and downwardly extended therefrom. Wheel  133  is inserted within a slot  131   c  disposed in an upper portion of a proximal end  131   b  of body  131 , and is rotatably adjoined with (preferably detachably coupled to) end  131   b  by a pin  133   a . A generally cylindrical aperture  131   d  extends through a lower portion of proximal end  131   b  of body  131 . Aperture  131   d  is spaced from slot  131   c.    
     Embodiments of a valve train in accordance with the present invention will now be described. These embodiments of a valve train are given solely for purposes of describing the best mode of the present invention and are not meant to be limiting to the scope of the claims in any way. 
     Referring to FIGS. 13A-13C, a first embodiment valve train  140  is shown. Valve train  140  comprises cylinder head  20  (see FIGS.  1 A through  1 C), a single camshaft  150 , six (6) intake valve assemblies  160 , and six (6) exhaust valve assemblies  170 . It is to be appreciated that valve train  140  can be constructed to include any number of combustion chamber covers  22 , intake valve assemblies  160 , and exhaust valve assemblies  170 . Camshaft  150  includes a shaft  151  rotatably adjoined to surface  21   a  of body  20 . Preferably, shaft  151  is detachably coupled to surface  21   a  of body  21 . Shaft  151  is also parallel with the arrangement of combustion chamber covers  22  and spaced therefrom. For each intake valve assembly  160 , camshaft  150  further includes an intake cam lobe  152  adjoined to shaft  151 . For each exhaust valve assembly  170 , camshaft  150  further includes an exhaust cam lobe  153  adjoined to shaft  151 . Intake cam lobes  152  and exhaust cam lobes  153  are conventionally configured as shown for a fixed valve timing and lift operation. Preferably, camshaft  150  is fabricated as a unitary member. Alternatively, shaft  151  can be slidably and rotatably adjoined to cylinder head  20 , and intake cam lobes  152  and exhaust cam lobes  153  can be configured for a variable valve timing and lift operation. Valve train  140  further comprises a fuel injector  180  for each combustion chamber cover  22 . Fuel injectors  180  are inserted within injector bores  28   a  and  28   b  (see FIGS.  1 A and  1 B). It is to be appreciated that two valve trains  140  or equivalents thereof can be utilized for a conventional “V” engine arrangement. 
     With continued reference to FIG. 13C, each intake valve assembly  160  includes a pair of intake valves  161   a  and  161   b . The head of intake valve  161   a  is removably seated within intake valve seat  24   a , and the head of intake valve  161   b  is removably seated within intake valve seat  24   b . An intake valve guide  162   a  is fitted within intake bore  26   a , and an intake valve guide  162   b  is fitted within intake bore  26   b . The stem of intake valve  161   a  is movably positioned within intake valve guide  162   a , and the stem of intake valve  161   b  is movably positioned within intake valve guide  162   b . The head of intake valve  161   a  is upwardly biased as seated within intake valve seat  24   a  by a spring  163   a  positioned within bore  26   a  and secured therein by a spring cap  164   a . The head of intake valve  161   b  is upwardly biased as seated within intake valve seat  24   b  by a spring  163   b  positioned within bore  26   b  and secured therein by a spring cap  164   b . The stem top of intake valve  161   a  extends through spring cap  164   a , and is movably positioned within slot  74   c  of crosshead  70  (see FIGS.  6 A through  6 D). The stem top of intake valve  161   b  extends through spring cap  164   b , and is movably positioned within slot  73   c  of crosshead  70  (see FIGS.  6 A through  6 D). A housing of a lash adjuster  165  is removably seated within intake lash adjuster seat  27   a  (see FIGS. 1A and 1B) and a domed end of lash adjuster  165  is movably positioned within indentation  72   c  of crosshead  70  (see FIGS. 6A through 6D) to thereby pivotally mount crosshead  70  to surface  21   a  of body  21 . Each intake valve assembly  160  also includes a rocker arm  166 . Rocker arm  166  is a modified version of rocker arm  120  having a different geometric configuration and physical dimensions than the geometric configuration and physical dimensions for rocker arm  120  as shown in FIGS. 11A and 11B. Rocker arm  166  is pivotally adjoined to surface  21   a  of body  21  by a shaft  167  that is detachably coupled to surface  21   a . An elephant foot  168  of rocker arm  166  abuts planar surface  71   a  of intake crosshead  70  (see FIGS. 6A through 6D) to thereby operatively adjoined rocker arm  166  to intake crosshead  70 . A wheel  169  of rocker arm  166  rotatably abuts intake cam lobe  152  to thereby operatively adjoin cam shaft  151  to rocker arm  166 . Each exhaust valve assembly  170  includes a pair of exhaust valves similarly disposed within exhaust valves seats  24   c  and  24   d  (see FIG.  1 C), a crosshead  70  similarly adjoined to the exhaust valves and surface  21   a , and a rocker arm similarly adjoined to crosshead  70 , surface  21   a , and cam shaft  151 . 
     Referring to FIGS. 13B and 13C, an exemplary operation of an intake valve assembly  160  will now be described herein. Shaft  151  is rotated by a source of rotational energy, e.g. a crankshaft. Intake cam lobe  152  synchronously rotates with shaft  151 . Intake cam lobe  152  cooperatively interacts with wheel  169  of rocker arm  166  so as to pivot rocker arm  166  back and forth about shaft  167 . Head  72  of crosshead  70  serves as a fulcrum. Accordingly, when elephant foot  168  of rocker arm  166  is downwardly pivoted, arms  73  and  74  of crosshead  70  exert a downward force on intake valves  161   a  and  161   b , respectively, that is sufficient to overcome the upward force applied to intake valves  161   a  and  161   b  by springs  164   a  and  164   b , respectively. As a result, the heads of intake valves  161   a  and  161   b  are unseated from intake valve seats  24   a  and  24   b  to thereby open intake valves  161   a  and  161   b . Conversely, when elephant foot  168  is upwardly pivoted, the upward force applied to intake valves  161   a  and  161   b  by springs  164   a  and  164   b , respectively, reseats the heads of intake valves  161   a  and  161   b  within intake valve seats  24   a  and  24   b  to thereby close intake valves  161   a  and  161   b . It is to be appreciated that exhaust valve assembly  170  operates in a same manner. For each paired inlet valve assembly  160  and exhaust valve assembly  170 , it is to preferred that the associated intake cam lobe  152  and outlet cam lobe  153  are uniformly spaced along shaft  151  with the peak lifts thereof being angularly misaligned whereby an opening of intake valves  161   a  and  161   b  partially overlaps with an opening the pair of exhaust valves of the corresponding exhaust valve assembly  170 . 
     Referring to FIGS. 14A-14C, a second embodiment valve train  190  is shown. Valve train  190  comprises cylinder head  30  (see FIGS.  2 A through  2 C), camshaft  150 , six (6) intake valve assemblies  200 , and six (6) exhaust valve assemblies  210 . It is to be appreciated that valve train  190  can be constructed to include any number of combustion chamber covers  32 , intake valve assemblies  200 , and exhaust valve assemblies  210 . Camshaft  150  includes shaft  151  rotatably adjoined to surface  31   a  of body  20 . Preferably, shaft  151  is detachably coupled to surface  31   a  of body  31 . Shaft  151  is also parallel with the arrangement of combustion chamber covers  32  and spaced therefrom. For each intake valve assembly  200 , camshaft  150  further includes an intake cam lobe  152  adjoined to shaft  151 . For each exhaust valve assembly  210 , camshaft  150  further includes an exhaust cam lobe  153  adjoined to shaft  151 . Intake cam lobes  152  and exhaust cam lobes  153  are conventionally configured as shown for a fixed valve timing and lift operation. Preferably, camshaft  150  is again fabricated as a unitary member. Alternatively, shaft  151  can be slidably and rotatably adjoined to cylinder head  30 , and intake cam lobes  152  and exhaust cam lobes  153  can be configured for a variable valve timing and lift operation. Valve train  190  further comprises a fuel injector  180  for each combustion chamber cover  32 . Fuel injectors  180  are inserted within injector bores  38   a  and  38   b  (see FIGS.  2 A and  2 B). It is to be appreciated that two valve trains  190  or equivalents thereof can be utilized for a conventional “V” engine arrangement. 
     With continued reference to FIG. 14C, each intake valve assembly  200  includes a pair of intake valves  201   a  and  201   b . The head of intake valve  201   a  is removably seated within intake valve seat  34   a , and the head of intake valve  201   b  is removably seated within intake valve seat  34   b . An intake valve guide  202   a  is fitted within intake bore  36   a , and an intake valve guide  202   b  is fitted within intake bore  36   b . The stem of intake valve  201   a  is movably positioned within intake valve guide  202   a , and the stem of intake valve  201   b  is movably positioned within intake valve guide  202   b . The head of intake valve  201   a  is upwardly biased as seated within intake valve seat  34   a  by a spring  203   a  positioned within bore  36   a  and secured therein by a spring cap  204   a . The head of intake valve  201   b  is upwardly biased as seated within intake valve seat  34   b  by a spring  204   b  positioned within bore  36   b  and secured therein by a spring cap  204   b . The stem top of intake valve  201   a  extends through spring cap  204   a , and is movably positioned within slot  94   c  of crosshead  90  (see FIGS.  8 A through  8 D). The stem top of intake valve  201   b  extends through spring cap  204   b , and is movably positioned within slot  93   c  of crosshead  90  (see FIGS.  8 A through  8 D). A housing of a lash adjuster  205  is removably seated within intake lash adjuster seat  37   a  (see FIGS. 2A and 2B) and a domed end of lash adjuster  205  is movably positioned within indentation  92   c  of crosshead  90  (see FIGS. 8A through 8D) to thereby pivotally mount crosshead  90  to surface  31   a  of body  31 . Each intake valve assembly  200  also includes a rocker arm  206 . Rocker arm  206  is a modified version of rocker arm  120  having a different geometric configuration and physical dimensions than the geometric configuration and physical dimensions for rocker arm  120  as shown in FIGS. 11A and 11B. Rocker arm  206  is pivotally adjoined to surface  31   a  of body  31  by a shaft  207  that is detachably coupled to surface  31   a . An elephant foot  208  of rocker arm  206  abuts planar surface  91   a  of intake crosshead  90  (see FIGS. 8A through 8D) to thereby operatively adjoined rocker arm  206  to intake crosshead  90 . A wheel  209  of rocker arm  206  rotatably abuts intake cam lobe  152  to thereby operatively adjoin cam shaft  151  to rocker arm  206 . Each exhaust valve assembly  210  includes a pair of exhaust valves similarly disposed within exhaust valves seats  34   c  and  34   d  (see FIG.  2 C), a crosshead  90  similarly adjoined to the exhaust valves and surface  31   a , and a rocker arm similarly adjoined to crosshead  90 , surface  31   a , and cam shaft  151 . 
     Referring to FIGS. 14B and 14C, an exemplary operation of an intake valve assembly  200  will now be described herein. Shaft  151  is rotated by a source of rotational energy, e.g. a crankshaft. Intake cam lobe  152  synchronously rotates with shaft  151 . Intake cam lobe  152  cooperatively interacts with wheel  209  of rocker arm  206  so as to pivot rocker arm  206  back and forth about shaft  207 . Head  92  of crosshead  90  serves as a fulcrum. Accordingly, when elephant foot  208  of rocker arm  206  is downwardly pivoted, arms  93  and  94  of crosshead  90  exert a downward force on intake valves  201   a  and  201   b , respectively, that is sufficient to overcome the upward force applied to intake valves  201   a  and  201   b  by springs  204   a  and  204   b , respectively. As a result, the heads of intake valves  201   a  and  201   b  are unseated from intake valve seats  34   a  and  34   b  to thereby open intake valves  201   a  and  201   b . Conversely, when elephant foot  208  is upwardly pivoted, the upward force applied to intake valves  201   a  and  201   b  by springs  204   a  and  204   b , respectively, reseats the heads of intake valves  201   a  and  201   b  within intake valve seats  34   a  and  34   b  to thereby close intake valves  201   a  and  201   b . It is to be appreciated that exhaust valve assembly  210  operates in a same manner. For each paired inlet valve assembly  200  and exhaust valve assembly  210 , it is preferred that the associated intake cam lobe  152  and outlet cam lobe  153  are uniformly spaced along shaft  151  with the peak lifts thereof being angularly misaligned whereby an opening of intake valves  201   a  and  201   b  partially overlaps with an opening the pair of exhaust valves of the corresponding exhaust valve assembly  210 . 
     Referring to FIGS. 15A-15C, a third embodiment valve train  220  is shown. Valve train  220  comprises cylinder head  40  (see FIGS.  3 A through  3 C), camshaft  150 , six (6) intake valve assemblies  230 , and six (6) exhaust valve assemblies  240 . It is to be appreciated that valve train  220  can be constructed to include any number of combustion chamber covers  42 , intake valve assemblies  230 , and exhaust valve assemblies  240 . Camshaft  150  includes shaft  151  rotatably adjoined to surface  41   a  of body  43 . Preferably, shaft  151  is detachably coupled to surface  41   a  of body  41 . Shaft  151  is also parallel with the arrangement of combustion chamber covers  42  and spaced therefrom. For each intake valve assembly  230 , camshaft  150  further includes an intake cam lobe  152  adjoined to shaft  151 . For each exhaust valve assembly  240 , camshaft  150  further includes an exhaust cam lobe  153  adjoined to shaft  151 . Intake cam lobes  152  and exhaust cam lobes  153  are conventionally configured as shown for a fixed valve timing and lift operation. Preferably, camshaft  150  is again fabricated as a unitary member. Alternatively, shaft  151  can be slidably and rotatably adjoined to cylinder head  40 , and intake cam lobes  152  and exhaust cam lobes  153  can be configured for a variable valve timing and lift operation. Valve train  190  further comprises a fuel injector  180  for each combustion chamber cover  42 . Fuel injectors  180  are inserted within injector bores  48   a  and  48   b  (see FIGS.  3 A and  3 B). It is to be appreciated that two valve trains  220  or equivalents thereof can be utilized for a conventional “V” engine arrangement. 
     With continued reference to FIG. 15C, each intake valve assembly  230  includes a pair of intake valves  231   a  and  231   b . The head of intake valve  231   a  is removably seated within intake valve seat  44   a , and the head of intake valve  231   b  is removably seated within intake valve seat  44   b . An intake valve guide  232   a  is fitted within intake bore  46   a , and an intake valve guide  232   b  is fitted within intake bore  46   b . The stem of intake valve  231   a  is movably positioned within intake valve guide  232   a , and the stem of intake valve  231   b  is movably positioned within intake valve guide  232   b . The head of intake valve  231   a  is upwardly biased as seated within intake valve seat  44   a  by a spring  233   a  positioned within bore  46   a  and secured therein by a spring cap  234   a . The head of intake valve  231   b  is upwardly biased as seated within intake valve seat  44   b  by a spring  234   b  positioned within bore  46   b  and secured therein by a spring cap  234   b . The stem top of intake valve  231   a  extends through spring cap  234   a , and is movably positioned within slot  105   c  of crosshead  100  (see FIGS.  9 A through  9 D). The stem top of intake valve  231   b  extends through spring cap  234   b , and is movably positioned within slot  104   c  of crosshead  100  (see FIGS.  9 A through  9 D). The housing of a lash adjuster  235   a  is removably seated within intake lash adjuster seat  47   a  (see FIGS. 3A and 3B) and a domed end of lash adjuster  235   a  is movably positioned within indentation  102   c  of crosshead  100  (see FIGS.  9 A through  9 D). The housing of a lash adjuster  235   b  is removably seated within intake lash adjuster seat  47   b  (see FIGS. 3A and 3B) and a domed end of lash adjuster  235   b  is movably positioned within indentation  103   c  of crosshead  100  (see FIGS. 9A through 9D) to thereby pivotally mount crosshead  100  to surface  41   a  of body  41 . Each intake valve assembly  230  also includes a rocker arm  236 . Rocker arm  236  is a modified version of rocker arm  120  having a different geometric configuration and physical dimensions than the geometric configuration and physical dimensions for rocker arm  120  as shown in FIGS. 11A and 11B. Rocker arm  236  is pivotally adjoined to surface  41   a  of body  41  by a shaft  237  that is detachably coupled to surface  41   a . An elephant foot  238  of rocker arm  236  abuts planar surface  101   a  of intake crosshead  100  (see FIGS. 9A through 9D) to thereby operatively adjoined rocker arm  236  to intake crosshead  100 . A wheel  239  of rocker arm  236  rotatably abuts intake cam lobe  152  to thereby operatively adjoin cam shaft  151  to rocker arm  236 . Each exhaust valve assembly  240  includes a pair of exhaust valves similarly disposed within exhaust valves seats  44   c  and  44   d  (see FIG.  3 C), a crosshead  100  similarly adjoined to the exhaust valves and surface  41   a , and a rocker arm similarly adjoined to crosshead  100 , surface  41   a , and camshaft  151 . 
     Referring to FIGS. 15B and 15C, an exemplary operation of an intake valve assembly  230  will now be described herein. Shaft  151  is rotated by a source of rotational energy, e.g. a crankshaft. Intake cam lobe  152  synchronously rotates with shaft  151 . Intake cam lobe  152  cooperatively interacts with wheel  239  of rocker arm  236  so as to pivot rocker arm  236  back and forth about shaft  237 . Heads  102  and  103  of crosshead  100  serves as a fulcrum. Accordingly, when elephant foot  238  of rocker arm  236  is downwardly pivoted, arms  104  and  105  of crosshead  100  exert a downward force on intake valves  231   a  and  231   b , respectively, that is sufficient to overcome the upward force applied to intake valves  231   a  and  231   b  by springs  234   a  and  234   b , respectively. As a result, the heads of intake valves  231   a  and  231   b  are unseated from intake valve seats  44   a  and  44   b  to thereby open intake valves  231   a  and  231   b . Conversely, when elephant foot  238  is upwardly pivoted, the upward force applied to intake valves  231   a  and  231   b  by springs  234   a  and  234   b , respectively, reseats the heads of intake valves  231   a  and  231   b  within intake valve seats  44   a  and  44   b  to thereby close intake valves  231   a  and  231   b . It is to be appreciated that exhaust valve assembly  240  operates in a same manner. For each paired inlet valve assembly  230  and exhaust valve assembly  240 , it is preferred that the associated intake cam lobe  152  and outlet cam lobe  153  are uniformly spaced along shaft  151  with the peak lifts thereof being angularly misaligned whereby an opening of intake valves  231   a  and  231   b  partially overlaps with an opening the pair of exhaust valves of the corresponding exhaust valve assembly  240 . 
     Referring to FIGS. 16A-16C, a first embodiment valve train  250  is shown. Valve train  250  comprises cylinder head  50  (see FIGS.  4 A through  4 C), single camshaft  150 , six (6) intake valve assemblies  260 , and six (6) exhaust valve assemblies  270 . It is to be appreciated that valve train  250  can be constructed to include any number of combustion chamber covers  52 , intake valve assemblies  260 , and exhaust valve assemblies  270 . Camshaft  150  includes shaft  151  rotatably adjoined to surface  51   a  of body  53 . Preferably, shaft  151  is detachably coupled to surface  51   a  of body  51 . Shaft  151  is also parallel with the arrangement of combustion chamber covers  52  and spaced therefrom. For each intake valve assembly  260 , camshaft  150  further includes an intake cam lobe  152  adjoined to shaft  151 . For each exhaust valve assembly  270 , camshaft  150  further includes an exhaust cam lobe  153  adjoined to shaft  151 . Intake cam lobes  152  and exhaust cam lobes  153  are conventionally configured as shown for a fixed valve timing and lift operation. Preferably, camshaft  150  is again fabricated as a unitary member. Alternatively, shaft  151  can be slidably and rotatably adjoined to cylinder head  50 , and intake cam lobes  152  and exhaust cam lobes  153  can be configured for a variable valve timing and lift operation. Valve train  250  further comprises a fuel injector  180  for each combustion chamber cover  52 . Fuel injectors  180  are inserted within injector bores  58   a  and  58   b  (see FIGS.  4 A and  4 B). It is to be appreciated that two valve trains  250  or equivalents thereof can be utilized for a conventional “V” engine arrangement. 
     With continued reference to FIG. 16C, each intake valve assembly  260  includes a pair of intake valves  261   a  and  261   b . The head of intake valve  261   a  is removably seated within intake valve seat  54   a , and the head of intake valve  261   b  is removably seated within intake valve seat  54   b . An intake valve guide  262   a  is fitted within intake bore  56   a , and an intake valve guide  262   b  is fitted within intake bore  56   b . The stem of intake valve  261   a  is movably positioned within intake valve guide  262   a , and the stem of intake valve  261   b  is movably positioned within intake valve guide  262   b . The head of intake valve  261   a  is upwardly biased as seated within intake valve seat  54   a  by a spring  263   a  positioned within bore  56   a  and secured therein by a spring cap  264   a . The head of intake valve  261   b  is upwardly biased as seated within intake valve seat  54   b  by a spring  264   b  positioned within bore  56   b  and secured therein by a spring cap  264   b . The stem top of intake valve  261   a  extends through spring cap  264   a , and is movably positioned within slot  115   c  of crosshead  110  (see FIGS.  10 A through  10 D). The stem top of intake valve  261   b  extends through spring cap  264   b , and is movably positioned within slot  114   c  of crosshead  110  (see FIGS.  10 A through  10 D). The housing of a lash adjuster  265   a  is removably seated within intake lash adjuster seat  57   a  (see FIGS. 4A and 4B) and a domed end of lash adjuster  265   a  is movably positioned within indentation  113   c  of crosshead  110  (see FIGS.  10 A through  10 D). The housing of a lash adjuster  265   b  is removably seated within intake lash adjuster seat  57   b  (see FIGS. 4A and 4B) and a domed end of lash adjuster  265   b  is movably positioned within indentation  112   c  of crosshead  110  (see FIGS. 10A through 10C) to thereby pivotally mount crosshead  110  to surface  51   a  of body  51 . Each intake valve assembly  260  also includes a rocker arm  266 . Rocker arm  266  is a modified version of rocker arm  120  having a different geometric configuration and physical dimensions than the geometric configuration and physical dimensions for rocker arm  120  as shown in FIGS. 11A and 11B. Rocker arm  266  is pivotally adjoined to surface  51   a  of body  51  by a shaft  267  that is detachably coupled to surface  51   a . An elephant foot  268  of rocker arm  266  abuts planar surface  11   a  of intake crosshead  110  (see FIGS. 10A through 10D) to thereby operatively adjoined rocker arm  266  to intake crosshead  110 . A wheel  269  of rocker arm  266  rotatably abuts intake cam lobe  152  to thereby operatively adjoin cam shaft  151  to rocker arm  266 . Each exhaust valve assembly  270  includes a pair of exhaust valves similarly disposed within exhaust valves seats  54   c  and  54   d  (see FIG.  4 C), a crosshead  110  similarly adjoined to the exhaust valves and surface  51   a , and a rocker arm similarly adjoined to crosshead  110 , surface  51   a , and cam shaft  151 . 
     Referring to FIGS. 16B and 16C, an exemplary operation of an intake valve assembly  260  will now be described herein. Shaft  151  is rotated by a source of rotational energy, e.g. a crankshaft. Intake cam lobe  152  synchronously rotates with shaft  151 . Intake cam lobe  152  cooperatively interacts with wheel  269  of rocker arm  266  so as to pivot rocker arm  266  back and forth about shaft  267 . Heads  112  and  113  of crosshead  110  serve as a fulcrum. Accordingly, when elephant foot  268  of rocker arm  266  is downwardly pivoted, arms  114  and  115  of crosshead  110  exert a downward force on intake valves  261   a  and  261   b , respectively, that is sufficient to overcome the upward force applied to intake valves  261   a  and  261   b  by springs  264   a  and  264   b , respectively. As a result, the heads of intake valves  261   a  and  261   b  are unseated from intake valve seats  54   a  and  54   b  to thereby open intake valves  261   a  and  261   b . Conversely, when elephant foot  268  is upwardly pivoted, the upward force applied to intake valves  261   a  and  261   b  by springs  264   a  and  264   b , respectively, reseats the heads of intake valves  261   a  and  261   b  within intake valve seats  54   a  and  54   b  to thereby close intake valves  261   a  and  261   b . It is to be appreciated that exhaust valve assembly  270  operates in a same manner. For each paired inlet valve assembly  260  and exhaust valve assembly  270 , it is preferred that the associated intake cam lobe  152  and outlet cam lobe  153  are uniformly spaced along shaft  151  with the peak lifts thereof being angularly misaligned whereby an opening of intake valves  261   a  and  261   b  does not overlap with an opening the pair of exhaust valves of the corresponding exhaust valve assembly  270 . 
     While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.