Patent Publication Number: US-6666064-B2

Title: Portable hydraulic crimping tool

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to hydraulic tools and, more particularly, to a compact portable hydraulic tool. 
     2. Brief Description of Earlier Developments 
     Hydraulic power tools are used in numerous applications to provide users with a desired mechanical advantage. One such application is in crimping tools used for making crimping connections such as for example crimping power connectors onto conductors. In this case, it is desired that the hydraulic crimping tools be portable in order to bring the tool to the job site. Conventional hydraulic crimping tools are generally heavy and thus cumbersome to handle during operation. The reason for this is that the crimping tools may be subjected to high loads during operation and are provided with structure capable of withstanding such loads. For instance, the movable adapter of a hydraulic crimping tool may often be subjected to considerable non-axial loads (i.e. loads which are not aligned with the axis of travel of the movable adapter in the tool). The non-axial loads on the movable adapter can cause the tool to bind or may even cause failure of the tool during operation. The approach taken to prevent misalignment and binding of the movable adapter under non-axial loads in conventional tools has been to provide the movable adapter and support frame with keying mechanism. However, this results in an increase in the size of both the adapter and support frame of the tool and a corresponding increase in weight. One example of a conventional hydraulic compression tool is shown in U.S. Pat. No. 5,934,136. This tool has a compression head with movable dies each having two guide plates slidably engaging with guide grooves formed into the frame of the compression head. 
     Another feature desired on hydraulic compression tools is the ability to rapidly advance the movable adapter when closing up gaps between the work piece, such as a crimping connector, and the movable adapter. This allows the user to perform the crimping operation faster, and using a smaller number of pump strokes which is important especially in the case of a manually operated hydraulic crimping tool. 
     U.S. Pat. Nos. 4,942,757 and 4,947,672, which are hereby incorporated by reference, disclose hydraulic tools with movable rams. FCI USA Inc. sells a hand operated hydraulic tool, type Y750 which has a rapid advance two stage pump and a type Y35 with a rotatable handle for rapid ram advance. 
     U.S. Pat. No. 5,979,215, which is also incorporated by reference herein in its entirety, discloses a hydraulic tool with an arm and a mechanical actuator in the hydraulic conduit system for contacting a rear end of the ram. Conventional hydraulic crimping tools which have a ram with a rapid advance feature may employ a multi-stage pump or a multi-stage ram piston in order to provide the rapid advance feature. The hydraulic fluid conduit system to route fluid from the multiple stages of the multi-stage pump to the hydraulic fluid contact surface of the ram is complex with numerous parallel conduits between the pump and ram. Accordingly, an extensive amount of machining or fabrication may be involved in forming such a conduit system in the hydraulic tool. The complexity of the hydraulic conduit system has commensurate impact on the time and cost of manufacturing the tool. In the case of a multi-stage ramp piston, the size and length of the ram is increased to accommodate the multiple stages. The longer, larger ram uses a correspondingly longer, larger hydraulic cylinder which in turn increases the size and hence the weight, as well as the cost of the tool. The instant invention overcomes the problems of conventional hydraulic crimping tools as will be described in greater detail below. 
     SUMMARY OF THE INVENTION 
     In accordance with the first embodiment of the present invention a hydraulic tool is provided. The hydraulic tool comprises a frame, and a movable adapter. The frame has a work space with an anvil adapter at one end and a substantially flat face guide surface on one side of the workspace. The movable adapter is used for working a piece in the workspace against the anvil adapter. The movable adapter is movably mounted to the frame to move in the workspace relative to the frame along an axis of translation. The movable adapter has a substantially flat face seating surface seated against the guide surface of the frame. When the movable adapter is moved, the seating surface of the movable adapter rides upon the guide surface. The seating surface and guide surface interface with each other in order to maintain the movable adapter in a predetermined orientation relative to the frame. 
     In accordance with a second embodiment of the present invention, a hydraulic tool is provided. The hydraulic tool comprises a frame, and a movable adapter. The frame has an anvil adapter and a substantially flat guide surface. The movable adapter is movably mounted to the frame to move relative to the frame along an axis of translation. The movable adapter is adapted for working a workpiece in cooperation with the anvil adapter and has a substantially flat support surface seated against the guide surface. The support surface and guide surface interface to prevent rotation of the movable adapter about the axis of translation. The frame includes a bearing surface adapted for maintaining the alignment of the movable adapter with the axis of translation. The bearing surface is disposed in the frame so that the movable adapter does not contact the bearing surface. 
     In accordance with a third embodiment of the present invention, a hydraulic tool is provided. The hydraulic tool comprises a frame, a ram assembly, and a hydraulic fluid conduit system. The frame has a hydraulic fluid reservoir connected to the frame. The ram assembly is movably mounted to the frame. The ram assembly comprises an outer ram, and an inner ram housed in the outer ram. Both inner and outer rams are movable relative to the frame. The hydraulic fluid conduit system is disposed in the frame between the ram assembly and the fluid reservoir. The outer ram is adapted to be advanced relative to the frame by the inner ram and by hydraulic fluid pressure against the outer ram. The outer ram is advanced by the inner ram pressing against the outer ram when hydraulic fluid pressure in the conduit system is below a predetermined pressure. The outer ram is advanced by hydraulic fluid against the outer ram when hydraulic fluid pressure in the conduit system is above the predetermined pressure. 
     In accordance with a fourth embodiment of the present invention, a hydraulic tool is provided. The hydraulic tool comprises a frame, a hydraulic fluid conduit system, a ram, and a rapid advance ram actuator. The frame has a hydraulic fluid reservoir connected to the frame. The hydraulic fluid conduit system extends through the frame from the reservoir. The ram is movably mounted to the frame. The ram is adapted to be moved relative to the frame by hydraulic fluid from the conduit system. The rapid advanced ram actuator is movably mounted to the frame for advancing the ram through at least part of the ram travel. The rapid advance ram actuator has one end contacting the ram and another end with an actuator hydraulic fluid contact surface for moving the rapid advance ram actuator relative to the frame using hydraulic fluid from the conduit system. The ram has a chamber formed therein. The rapid advance ram actuator is located inside the chamber in the ram. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing aspects and other features of the present invention are explained in the following description, taken in connection with the accompanying drawings, wherein: 
     FIG. 1 is a perspective view of a hydraulic crimping tool incorporating features of the present invention; 
     FIG. 2 is a cross-sectional elevation view of the hydraulic crimping tool in FIG. 1; 
     FIGS. 2A-2B are two cross sectional views of a power section and conduit system of the hydraulic crimping tool taken respectively along lines A—A and B—B in FIG. 2; 
     FIGS. 2C-2E are other cross sectional views of the power section taken respectively along lines C—C, D—D, and E—E; 
     FIGS. 2F-2G are still other cross sectional views of the power section respectively taken along lines F—F in FIG. 2C, and lines G—G in FIG. 2F; 
     FIG. 3 a perspective view of a section of the frame of the hydraulic crimping tool in FIG. 1; and 
     FIG. 4 is a cross-sectional view of a hydraulic crimping tool in accordance with another embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, there is shown a perspective view of a hydraulic crimping tool  10  incorporating features of the present invention. Although the present invention will be described with reference to the single embodiment shown in the drawings, it should be understood that the present invention can be embodied in many alternate forms of embodiments. In addition, any suitable size, shape or type of elements or materials could be used. 
     The present invention is described below with particular reference to a portable crimping tool  10 , though the invention is equally applicable to any suitable type of hydraulic power tool. Referring also to FIG. 2, which shows a cross-sectional elevation view of the hydraulic crimping tool  10 , the tool generally comprises a head section  12 , a power section  14  and a handle (not shown) The head section  12  is connected to the power section  14 . The handle section extends from the power section. The head section generally has a static or anvil adapter  16  and movable adapter  18 . The anvil adapter  16  is located at one end of the head section. The movable adapter  18  is movably seated in the head section. The power section is a hydraulic power section which generally has a hydraulic cylinder  20 , a ram assembly  22 , and a pump body  24 . The ram assembly  22  is located in the cylinder  20  and is connected to the movable adapter  18  in the head section. The ram assembly  22  has an outer ram  30  and a ram actuator  28 . The pump body  24  is connected to the hydraulic cylinder  20 . The power section  14  has a pump  26  located in the pump body for pumping hydraulic fluid through the pump body into the hydraulic cylinder. The handle may include a reservoir  27  for hydraulic fluid used in the power section. The handle section may include an actuator (not shown) for actuating the pump  26  in the power section. The actuator may be manually operated such as by using a lever incorporated into the handle. Otherwise, the actuator may be powered by a suitable motor, such as for example, an electromechanical motor. A suitable example of an electromechanical motor and linkage for operating the hydraulic tool pump is provided in U.S. Patent Application entitled “HYDRAULIC COMPRESSION TOOL AND HYDRAULIC COMPRESSION TOOL MOTOR”, filed on Apr. 9, 2002 as application Ser. No. 10/119,456, which is incorporated by reference herein in its entirety. When the pump  26  is operated, hydraulic fluid from reservoir  27  is pumped through the pump body  24  to the hydraulic cylinder  20  and the ram assembly  22  therein. The ram actuator  28  of ram assembly  22  is pressed by hydraulic fluid against outer ram  30  thereby advancing the outer ram. The movable adapter  18  connected to the outer ram  30  of the assembly is thus advanced towards the anvil  16 . When the movable adapter  18  encounters resistance such as from a work piece between the anvil  16  and movable adapter, hydraulic fluid is sent through the ram actuator  28  to the outer ram  30  thereby again advancing the outer ram and the movable adapter  18  towards the anvil. The movable adapter  18  is guided along a guide surface  32  of head section  12  which prevents the movable adapter  18  from spinning under non-axial loads. The outer ram  30  is seated against a bearing surface  34  of head section  12  to support non-axial loads on the movable adapter  18  as will be described in greater detail below. 
     In greater detail now, as seen best in FIG. 3, in this embodiment, the head section  12  of the tool  10  generally has a base or collar section  42  for connecting the head section to the rest of the tool, and an upper section  44 . The upper section  44  may have a general scallop or general C shape, as shown in FIG. 3, which defines a workspace  48  in the head section  12 . In alternate embodiments, the head section structure may have any other suitable configuration providing a workspace in which work pieces may be placed into the head section. The upper section  44  depends from the collar section  42 . The upper section  44  has a longitudinal portion  45 , which forms the back or spine of the C shape, and an upper end  46 . The longitudinal portion  45  may be a space frame with inner and outer walls  50 ,  52  tied to each other by truss supports  58 ,  59 . The truss supports  58 ,  59  form a series of voids in the longitudinal portion  45  which significantly reduces the weight of the head section  12  without loss in structural strength and rigidity. The outer wall  52  has curved end sections  54 ,  56  which transition the outer wall into the inner wall  50  at the ends of the longitudinal portion  45 . Reinforcing ribs  60  may be formed along the inner wall  50 , at both sides  61  of the longitudinal part  45 , in order to further increase the rigidity of the head section  12 . 
     The upper end  46  of the head section  12  is cantilevered from the longitudinal portion and has a generally curved shape as is shown in FIG.  3 . As can be realized from FIG. 3, the upper end  46  forms the anvil adapter  16  at the top of the workspace  48  in the head section. The anvil adapter has a curved seating surface  62 . The curved surface  62  may be of constant radius projected from centerline C (see FIG.  3 ). As seen in FIGS. 1 and 3, in this embodiment, a bore  63  is formed through the upper end  46  to the seating surface  62  of the anvil adapter  16  for mounting a die (not shown) to the anvil adapter. The curved seating surface  62  may provide a working surface against which work pieces having a round outer surface with a diameter complementing surface  62  may be seated. In the case where the work piece does not have a round outer surface which complements surface  62 , a die may be mounted using bore  63  to the anvil adapter allowing the work piece to be stably supported from the anvil adapter. The anvil adapter  16  has outer and inner stop surfaces  64 ,  66  which stop the travel of the movable adapter  18  in the work space  48  (see FIG.  1 ). The inner surface  32  of the inner wall  50  of longitudinal portion  45  extends from the inner stop surface  66  of the anvil adapter to the upper edge  70  of the collar section  42 . The inner surface  32  is substantially flat as seen in FIG.  3  and provides a guide surface to adapter  18  as will be described below. A radiused transition  72  blends the inner surface  32  into the seating surface  71  along the upper edge  70  of the collar section  42 . The inner surface  32  is substantially parallel with the axis of translation A (see FIG. 3) of the movable adapter  18 , and the centerline C of the anvil surface  62 . 
     Still referring to FIGS. 1-3, the upper section  44  is integral to the collar section  42 . By way of example, the head section  12  may be a one piece member formed by any suitable process such as casting or drop forging. As seen best in FIG. 3, in this embodiment the collar section  42  has a generally cylindrical shape with a cylindrical edge  74  formed therein. In alternate embodiments, the base section of the head section may have any other suitable shape for mating the head section to the power section of the tool. In the preferred embodiment, the cylindrical collar section  42  has a lower part  76  and an upper part  78 . As can be seen in FIG. 3, for a major portion of its circumference, the upper part has a smaller exterior diameter than the lower part  76 . This results in the exterior of the upper part having a stepped in portion  78 S relative to the exterior of the lower part  76 . Similar to the exterior of the collar section, the bore  74  also has a lower portion  74 L, located in the lower part  76  of the collar, and an upper portion  74 U located in the upper part  78 . The lower portion  74 L has a larger diameter than the upper portion  74 U. An annular flange  80 , formed by any suitable means, such as machining, in the interior surface of the collar section separates the lower portion  74 L from the upper portion  74 U (see FIG.  2 ). The lower portion  74 L of the bore is sized to matingly receive the upper end of the power section  14  therein. The inner surface  82  is threaded with suitable internal threads (such NPT series internal threads for example) in order to provide a threaded engagement with the power section  14 . The upper portion  74 U of the bore is sized to form a close running fit with the ram  30  of the power unit. The inner surface  84  (see FIG. 2) is substantially smooth and forms a bearing surface for ram  30  as will be described in greater detail below. An annular groove  85  is formed into inner surface  84  for a wiper seal  86  or O-ring. As noted before, the collar section  42  ha a seating surface  71  at the upper end  70  for seating the movable adapter  18 . 
     As seen best in FIGS. 1-2, the movable adapter  18  may be a one-piece member which may be cast, forged, or fabricated in any other suitable manner. The movable adapter  18  has an upper or working end  90  which faces towards the anvil adapter  16  at the top of the workspace  48  when the movable adapter is mounted in the head section  12 . The upper end  90  of the movable adapter  18  has a working surface  92  which in this embodiment is curved similar but opposite to the curved surface  62  of the anvil. The upper end  90  of the movable adapter also has inner  90 I and outer stops  90 O to abut respectively against stops  64 ,  66  of the anvil  16  and stop advance of the movable adapter. The lower end  94  of the movable adapter has a flat seating surface  94 S which is seated against surface  71  (see FIG. 3) at the upper end  70  of the collar when the movable adapter is in a retracted position shown in FIG.  2 . The movable adapter  18  also has a boss  92  projecting from the surface  94 S at the lower end  94 . A through hole is provided in the movable adapter  18  for a mounting fastener  93  (such as a machine screw) used to secure the adapter  18  to the ram  30 . The through hole may extend through boss  92 . The lower end  94  of the adapter  18  also has a rounded inner bottom corner  95  which conforms to radiused transition  72  of the head section  12 . As seen in FIGS. 1-2, the body of the movable adapter  18  between the upper and lower ends  90 ,  94  has an outer surface with a curved or rounded portion  96  and a flat face  98 . This configuration provides the adapter  18  with a polarizing feature relative to its installation in head section  12 . As can be seen in FIG. 2, the adapter  18  can only be installed into head section  12  with the flat face  98  positioned towards the inner surface  32 . The flat face  98  is positioned on the adapter so that when the adapter is fitted to the ram  30 , the flat face  98  of the adapter is seated substantially flush against the inner surface  32  of the longitudinal portion  45  of the head section  12 . As can be realized from FIGS. 1-2, the interface between the flat inner surface  32  and the flat face  98  of the movable adapter, maintains the movable adapter  18  generally aligned with the anvil  16  and prevents any rotation (about axis A) of the movable adapter  18  as it is advanced by the ram  30  towards the anvil  16 . 
     Referring now again to FIG. 2, the hydraulic power section  14  which is mated to the collar section  42  of the head section  12  has a housing  15  which includes both the hydraulic cylinder  20  and the pump body  24 . As noted before, the power section  14  also has ram assembly  22 . The ram assembly  22  is movably mounted to the housing  15  as will be described in greater detail below. Ram assembly  22  generally comprises outer ram  30 , spring  100 , spring holder  102  and rapid advance ram actuator  28 . As seen in FIG. 2, the spring holder  102  is an elongated, one-piece member having a generally cylindrical shape. The holder  102  may be made of any suitable corrosion resistant metal such as chromium or nickel alloys. The holder  102  has a retention end  104  (shown as being threaded for example purposes), an intermediate section  106 , and a main section  108 . The intermediate section  106  is located between the threaded end  104  and main section  108 . As seen in FIG. 2, the threaded end  104  has a smaller cross-sectional diameter than intermediate section  106 . The threaded end  104  is machined to have an exterior thread of any suitable exterior thread series. The outer surface of the intermediate section  106  is substantially smooth to form a bearing surface for stably holding the spring holder in the housing  15  as will be described in greater detail below. As seen in FIG. 2, in this embodiment, an O-ring groove for O-ring  105  is machined into the exterior of the intermediate section  106 . The groove is located adjacent to the threads on the threaded end  104  of the holder  102 , though the groove may be located at any other suitable position along the length of the intermediate section. Intermediate section  106  is narrower than the main section  108  of the holder  102 . Accordingly, an annular shoulder separates the intermediate section  106  from the main section  108 . The annular shoulder forms a seating surface  110  facing toward the threaded end  104  of the holder  102 . The main section  108  of the holder  102  terminates in flanged end  103 . An external radial flange  112  projects out from the main section at the flanged end. The flange  112  may extend continuously around the circumference of the main section or may be segmented into sections distributed equally around the circumference. The flange  112  has a spring support surface  116  facing the threaded end  104  of the holder and ram seating surface  114  located on the flange opposite the support surface  116  (see FIG.  2 ). As can be seen in FIG. 2, the main section  108  has a sufficient length so that the spring support surface  116  is located beyond the upper end  118  of the hydraulic cylinder  20  when the spring holder is installed in housing  15 . As seen in FIG. 2, the spring holder  102  has a chamber  120  formed therein which is a hydraulic cylinder for the rapid advance actuator  28 . The opening  122  of the chamber  120  is located in the flanged end  103  of the holder. The chamber  120  is positioned within the main section  108  of the holder  102  and the bottom  124  of the chamber is located so that rapid advance actuator  28  may be received completely in the chamber  120 . The spring holder  102  also has a hydraulic fluid passage  126  which communicates with chamber  120  as seen in FIG.  2 . The passage  126  extends from the bottom  124  of the chamber to the entry port  127  at the edge of the threaded end  104 . 
     Still referring to FIG. 2, the spring  100  in the ram assembly  22  may be a helically wound coil spring made from suitable spring wire to provide a desired spring stiffness. The length of the spring  100  is sized to allow the outer ram  30  full range of travel in the hydraulic cylinder  20  without deformation of the spring. The rapid advance ram actuator  28  generally includes an actuator body  128 , spring loaded ball valve  130  and set screw  136 . The actuator body  128  is preferably a one-piece member made from suitable corrosion resistant metal. The body  128  has a diameter sized to form a close sliding fit within chamber  120  in the spring holder  102 . The length of the actuator body  128  is sufficient to advance the outer ram  30  (as will be described in greater detail below) through the full range of ram travel allowed by hydraulic cylinder  20 . The exterior of the body  128  may be substantially smooth except for an O-ring groove for O-ring  138  which forms a hydraulic seal between the body  128  and chamber  120  in the spring holder  102 . As seen in FIG. 2, the actuator body has a hydraulic fluid passage  132  extending through the body. The passage  132  has an entry port  142  in the hydraulic fluid contact surface  140  of the body. The passage  132  includes an expanded chamber with an appropriate seat for the spring loaded ball valve  130 . The passage terminates in a threaded hole for set screw  136  used to set the pressure at which the valve  130  opens. The passage  132  also has outlet ports  134  which open on the exterior of the actuator body  128  above the O-ring  138  as shown in FIG.  2 . If desired, the set screw  136  may also have a through bore which when the set screw is installed in the body  128  communicates with passage  132  so that fluid flowing through passage  132  may exit through the set screw  132 . 
     The outer ram  30  is preferably a one-piece member made from suitable corrosion resistant metal. As seen in FIG. 2, the ram  30  has an upper shaft section  144 , and an enlarged lower piston section  146 . The piston section  146  projects radially outward relative to the shaft section  144 . The exterior of the piston section is sized to make sliding contact with the wall of the hydraulic cylinder  20 . An O-ring groove  148  is formed into the piston exterior for O-ring  150  which forms a hydraulic seal between the piston  146  and cylinder  20 . This provides the piston section  146  with a hydraulic fluid contact surface  152  extending below the O-ring  150 . The upper shaft section  144  of ram  30  is sized to form a close sliding fit with the upper portion  74 U of the bore in the collar section  4 L. The upper end of the shaft section  144  provides a mating surface  158  for mounting movable adapter  18 . The mating surface  158  has a recess  160  conforming to boss  92  of the movable adapter (see FIG.  2 ). A blind threaded hole may be provided into the mating surface  158  for fastener  93 . The outer ram  30  has an inner chamber  156  formed therein. The opening of the inner chamber is at the rear end  154  of the ram  30 . The length of the inner chamber  156  is sufficient to admit the main section  108  of the spring holder  102  therein when the ram  30  is fully retracted as shown in FIG.  2 . As can be realized from FIG. 2, the surface of the chamber  156  is part of the hydraulic fluid contact surface  152  of the ram  30 . The ram assembly  22  may be assembled by inserting the rapid advance actuator  28  into the chamber  120  in the spring holder  102 . The spring holder  102  may then be placed with the flanged end  103  first into the chamber  156  of the outer arm  30 . The spring  100  may be placed into the chamber  156 . One end of the spring  100  is seated against support surface  116  of the spring holder  102 . With the spring  100  in the chamber  156 , retention ring  158  is installed into the chamber to hold the spring  100 , and hence, also the spring holder  102  and actuator  28  in the ram  30 . As seen in FIG. 2, the ring  158  is installed into a groove in the wall of the chamber  156 . The ram assembly may then be installed into the housing  15 . 
     Referring now to FIGS.  2  and  2 A- 2 G, the housing  15  of the power section  14  may be a one-piece member which as noted before includes the hydraulic cylinder  20  and the pump body  24 . In alternate embodiments the power section may have a housing assembly comprising a number of housing parts. The upper portion  117  of the housing  15  is configured to mate with the collar section  42  of the tool head section  12 . Accordingly, the upper portion  117  of the housing may be machined with external threads complementing internal threads on the interior surface  82   5  of the collar section  42 . As seen in FIG. 2, the hydraulic cylinder  20  is located in the upper portion of the housing  15 . When mated to the head section  12 , the surface of annular flange  80  in the collar section forms the upper end of the cylinder. The length of the cylinder is such that the ram  30  is provided with sufficient travel to advance the movable adapter  18  from the retracted position shown in FIG. 2 to a position (not shown) abutting the stops  64 ,  66  of the anvil  16 . The housing  15  has a bore  162  opening into the bottom of the hydraulic cylinder  20  for mounting the spring holder  102 , and hence the ram assembly  22  into the housing. The bottom part of the bore  162  is threaded to complement the threaded end  104  of the spring holder. The upper part  163  of the bore  162  conforms closely to the exterior of intermediate section  106  of the spring holder. The O-ring  105  on the holder  102  forms a hydraulic seal in bore  162  preventing hydraulic leaks between the hydraulic cylinder  20  and pump body  24  around the spring holder  102 . 
     The pump body  24  of housing  15  includes a hydraulic fluid conduit system  25  connecting the hydraulic cylinder  20  to the fluid reservoir  27 . The pump  26  is located in the conduit system  25 . The pump  26  is a one stage pump, and the preferred embodiment will be described below with specific reference to the one stage pump, although multi-stage pumps may be used equally well with the present invention. The conduit system  25  preferably has one suction conduit  210  and one supply conduit  212 . The conduit system  25  has a primary drain or return conduit  214  and a secondary drain conduit  216 . As seen in FIG. 2E, the suction conduit  210  extends directly between the reservoir  27  and the hydraulic chamber  20 . The suction conduit  210  has a check valve  218  which is closed by fluid pressure in the hydraulic cylinder. FIGS. 2A and 2E show that the supply conduit  212  with a portion  212 A which communicates with suction conduit  210  at a T-junction. As seen in FIG. 2A, immediately downstream of the junction to suction conduit  210 , the supply conduit portion  212 A has a check valve  220 . Check valve  220  is closed when fluid pressure in the supply conduit portion  212 A is greater than pressure in the suction conduit  210 . The supply conduit has pump chamber  222  for pump  26 . The pump chamber  222 , and hence pump  26 , is located in portion  212 A between check valve  220  and check valve  224 . As can be realized, check valve  220  isolates the supply conduit portion  212 A from the suction conduit  210  when the pump  26  is depressed into chamber  222  and pumps fluid through the supply conduit  212 . Check valve  224  closes the supply conduit portion  212 A (preventing reverse flow) when the pump  26  is raised in chamber  222  causing suction in the supply conduit. Downstream of valve  224 , is the supply conduit portion  212 B is routed to discharge port  212 D in the bottom of bore  162  which is located at the bottom of hydraulic cylinder  20  (see FIGS.  2 B and  2 D). The supply conduit portion  212 B is also joined to both primary and secondary drain conduits  214 ,  216  (see FIGS. 2D,  2 F and  2 G). As seen in FIG. 2G, secondary drain conduit  216  extends directly between the bottom of the hydraulic chamber  20  and the reservoir. The conduit  216  has a check valve  226  which is closed when fluid from the supply conduit  212  pressurizes the drain conduit  216  downstream of the check valve. In alternate embodiments, the check valve may be positioned to isolate the drain conduit from the supply conduit by pressure in the hydraulic chamber. The secondary drain conduit  216  may also include a pressure sensing solenoid valve  228  which opens to drain the supply conduit portion  212  when an over pressure is sensed in the supply conduit or hydraulic chamber. The primary drain conduit  214  is connected by section  214 I to the supply conduit portion  212 B as shown in FIG.  2 D. The primary drain conduit  214  thus communicates with bore  162  through the downstream section of the supply conduit  212 . The primary drain conduit  214  drains into reservoir  27 . The drain conduit  214  includes a plunger actuated valve  230  which isolates the junction  214 I to the supply conduit  212  from the reservoir  27 . 
     Referring again to FIG. 2, the ram assembly  22  may be installed into housing  15  by threading the threaded end  104  of the spring holder  102  into the threaded part of bore  162 . Compression spring  100  may generate sufficient friction between the outer ram  30  and spring holder  102  to allow the holder to be threaded by merely turning the outer ram. Otherwise, the outer ram and spring holder may be provided with radially interlocking features for turning the spring holder from the outer ram while allowing the ram to slide axially relative to the spring holder. When the spring holder is installed to the housing  15 , surface  116  of the flange  112  on the holder  102  presses against spring  100 . Thus, the spring  100  is compressed against ring  158  thereby biasing the outer ram  30  against surface  114  of the holder  102  (see FIG.  2 ). End surface  122  of the rapid advance actuator  28  is substantially flush or otherwise projecting slightly beyond the spring holder  102  and hence is also in contact with the top  157  of the chamber  156  in the outer ram. The O-ring  150  on the ram  30  forms a hydraulic seal with hydraulic chamber  20 . The O-ring  105  seals between the spring holder  102  and bore  162 . Passage  126  in the holder  102 , and hence passage  132  in the ram actuator  28  communicate with the discharge port  212 D of supply conduit  212 . As can be realized from FIG. 2, the O-ring  105  isolates the discharge port  212 D of the supply conduit  212  from the hydraulic chamber. Hydraulic fluid pumped through the supply conduit  212  must enter passage  126  in the spring holder  102 . 
     After installation of the ram assembly  22  into housing  15 , the head section is mounted by threading collar section  42  onto the upper portion  117  of the housing. As seen in FIG. 2, the upper end of the ram shaft  144  extends through the bore  74  in the collar section. The ram shaft  144  is thus seated on bearing surface  34  of the collar section  42 . The movable adapter  18  is installed in the head section  12  as shown in FIG. 2, and connected to the outer ram  30  by inserting fastener  93 . The threaded interface between head section  12  and housing  15 , and between the movable adapter  18  and ram  30 , allow the head section and movable adapter to swivel about axis A relative to the housing  15  and ram  30 . When the head section  12  is rotated about axis A, the head section rotates around outer ram  30 . Outer ram  30  does not rotate relative to housing  15 . Thus, when the head section is rotated about axis A, sliding contact may occur between the ram shaft  144  and collar section  42  and not between the piston section  146  of the ram  30  and the hydraulic cylinder  20 . This avoids damage to the smooth surfaces of the ram&#39;s piston section  146  and the hydraulic cylinder  20  when the head section is swiveled on the housing  15 . Thus, the head section  12  of the tool  10  may be swiveled as many times as desired in order to properly position work pieces (not shown) relative to the adapters  16 ,  18  without having to reposition the entire tool in order to avoid spinning the ram piston surface inside the hydraulic cylinder surface which may result in damage to both. 
     The tool  10  is operated by actuating the pump  26  (either manually or with a suitable motor). The pump  26  is primed by moving the pump outward in chamber  222  which draws fluid through valve  220  from the suction conduit  210  (and reservoir  27 ) into the supply conduit  210 . Pressing the pump  26  inwards into chamber  222  displaces the fluid downstream through valve  224  (valve  220  is closed by the pumping pressure) and supply conduit  212  and out of discharge port  212 D (see FIGS. 2A,  2 C,  2 D). Discharge valve  230  is shut preventing fluid from being pumped from the supply conduit to the drain conduit  214 . Check valve  226  (see FIG. 2G) is shut by the pressure in the supply conduit  212  preventing fluid from being pumped directly into the hydraulic cylinder  20 . From discharge port  212 D the fluid enters passage  126  in the spring holder  102 . Passage  126  directs the hydraulic fluid into chamber  120  against the hydraulic fluid contact surface  140  of the rapid advance ram actuator  28 . Fluid also enters passage  132  in the actuator  28  but is prevented from flowing further by check valve  130  which is shut. The pumping action of pump  26  thus feeds fluid under pressure into chamber  120  pressing against actuator  28  which in turn presses against the outer ram  30 . The actuator  28  is advanced along axis A relative to the spring holder by the fluid pumped chamber  120 . The actuator  28  in turn advances the outer ram  30  and the movable adapter  18  relative to the head section  12 . As noted before, the pressure set point for opening valve  130  is larger than the pressure used in chamber  120  to advance the ram  30  with actuator  28  when there is little to no resistance forces exerted against the movable die  18  in the workspace  48  (i.e. the movable die  18  is unloaded). When the movable die  18  encounters resistance, the pumping action of pump  26  causes the pressure in the chamber  120  and hence passage  132  to rise and open the valve  130 . This allows fluid to flow through the ram actuator  28  and discharge from ports  134  as well as any bores (not shown) in set screw  136 . The hydraulic fluid then enters into chamber  156  of the outer ram  30  and thus into the hydraulic cylinder  20 . The significantly larger area of the portion of the hydraulic fluid contact surface  154  normal to axis A (i.e. the piston face) causes the ram  30  to advance readily even against high resistance forces with little further increase in pressure although the pump  26  may be capable of generating any desired pressure in hydraulic chamber  20 . As can be realized from FIG. 2, the face area ratio between the pump  26  and ram actuator  28  is much smaller than the face area ratio between the pump  26  and outer ram  30 . Hence, for a given pump stroke of pump  26 , the ram actuator  28  (with valve  130  closed) will advance ram  30  a larger distance along axis A than when the ram  30  is advanced by pressure in the hydraulic cylinder alone. By way of example, for a pump having a 0.25 inch diameter, a ram with a piston face diameter of 2.0 inches, and a ram actuator face diameter of 0.3 inch, the actuator to pump face area ratio is about 1.44 and the ram to pump face area ratio is about 64. Hence, for a pump stroke of an 1.0 inch it takes about 1.4 pump strokes to advance the actuator  28 , and hence ram  30 , about 1.0 inch. It takes about 64 pump strokes to advance the outer ram  30  1.0 inch without using the actuator  28 . In other words, when the ram is not under load, and valve  130  is closed, the ram  30  is advanced by rapid advance ram actuator  28  at a rate 44 times faster for a given pump stroke then when the ram  30  is loaded and valve  130  is open. Moreover, the interior placement of the ram actuator  28  inside the outer ram  30  allows the size of housing  15  to be reduced with a corresponding reduction in the weight of the housing and of the tool  10  as a whole. Machining of the housing  15  is also simplified because the chamber  120  for the ram actuator  28  is machined into the spring holder  102 , not the housing  15 . The spring holder  102  is smaller and lighter than the housing  15 , allowing the holder to be handled easier than the housing during machining. The outer shape of the holder  102  also allows the chamber  120  to be machined more precisely in the holder than in the housing. 
     As noted before, advance of ram  30  moves the movable adapter  18  along axis A towards anvil adapter  16 . Flat face  98  of the adapter  18  rides over surface  32  of the head section  12 . As can be realized from FIGS. 1 and 2, as the movable adapter  18  encounters eccentric loads which tend to rotate the movable adapter  18  about axis A, the flat faces  98 ,  32  respectively on the adapter  18  and head section  12  interact (generate a moment couple) to resist rotation of the movable adapter. Other eccentric loads tending to displace the movable adapter  18  in directions orthogonal to axis A are transferred as shear loads through boss  92  to the ram shaft  144  which is seated against large bearing surface  34  in the head section collar  42 . Thus, eccentric loads on the movable adapter are prevented from binding or damaging the tool  10  during operation. Return of the movable adapter to the position shown in FIG. 2 is achieved by pressing the plunger actuator  230 A to open drain valve  230 . As can be realized from FIGS. 2C,  2 D and  2 G, when valve  230  is opened fluid pressure in supply conduit  212  causes fluid to flow through section  214 I into the primary drain conduit  214  to reservoir  27 . Fluid under pressure also flows out of chamber  120  (valve  130  in the actuator  28  shuts as pressure in the supply conduit drops when drain valve  230  is opened) through passage  126  (see FIG. 2) back into the supply conduit and as noted above into the drain conduit  214 . As chamber  120  becomes evacuated of fluid, the ram actuator  28  is returned into the chamber  120  with the low pressure in the supply conduit  212 , pressure in the hydraulic cylinder  20  becomes sufficient to open check valve  226  in drain conduit  216 . When valve  226  is open, fluid flows out from the hydraulic cylinder  20 , allowing the ram to return into the cylinder, through conduit  216  to supply conduit  212  (see FIGS. 2F,  2 G) and then through drain conduit  214  as previously described to reservoir  27 . 
     As has been described above, the seating surface  32 ,  98  on the head section and movable adapter  18 , the bearing surface  34  within the head section, the incorporation of the rapid advance ram actuator within the ram assembly  22 , are just some of the many features resulting in a hydraulic tool  10  with a two speed arm that can be rapidly advanced under no load, while the tool itself is very compact, and hence light and easy to use. The conduit system which is machined into the pump body  24  of the tool has a small number of conduits which simplifies manufacture of the pump body with a commensurate reduction in the time and expense of fabricating the tool. 
     Referring now to FIG. 4, there is shown a cross-sectional view of another embodiment. The tool  10 A in FIG. 4 is similar to tool  10  shown in FIGS. 1-3 and described above, and similar items are similarly numbered. As seen in FIG. 4, the movable adapter  18 A in the head section  12 A is joined to the ram  30 A by other means than those used in tool  10  in FIG.  7 . The connection of the movable adapter  18 A to the ram  30  is another example of a suitable joint between the adapter and ram which allows the movable adapter  18 A to remain rotationally fixed to the head section  112 A while allowing the adapter  18 A and the head section  12 A to rotate relative to ram  30 A. In the embodiment shown in FIG. 4, the movable adapter  18 A has a bore  92 A formed into seating surface  74 A. The bore  92 A may have an annular groove  92 R for ball bearings  93 A. In alternate embodiments, the inside of the bore may be smooth. Conversely, the end of the ram  30 A facing the movable adapter has a post or boss  160 A sized to form a close running fit inside bore  92 A. The boss  160 A on the end of the ram also has a series of annular scallops or pockets for seating ball bearings  93 A. In alternate embodiments, no ball bearings may be used. The movable adapter may have a passage (not shown) extending radially outward from groove  92 R through which bearings  93 A may be introduced into the groove. As the bearings  93 A are introduced into groove  92 R, the adapter  18 A may be rotated relative to ram  30 A (by rotating the head section  12 A for example) such that the bearings  93 A are individually seated into the pockets on boss  160 A. As can be seen in FIG. 4, the bearings  93 A allow the adapter  18 A and hence the head section  12 A of the tool  10 A to rotate freely relative to ram  30 A which may remain fixed in the power section  14 A. 
     Still referring to FIG. 4, in this embodiment the ram assembly  22 A in the power section  14 A has a spring holder  102 A with a retention end  104 A. In this embodiment, the retention end  104 A is not threaded. Retention end  104   a  may be cylindrical or may have any other suitable shape such as square or rectangular. As seen in FIG. 4, the retention end  104 A may have a recess  103 A for a lock pin (not shown) which extends laterally from the exterior into the retention end  104 A of the spring holder  102 A. The recess  103 A may be blind and may not communicate with the hydraulic fluid passage  126 A in the spring holder  102 A. The pump body  24 A of the power section  14 A may have a chamber  105 A drilled or otherwise formed therein for the lock pin (not shown) used to lock the spring holder  102 A, and hence (as described before) the ram assembly  22 A in the power section  14 A. The lock pin chamber  105 A may be plugged with a set screw  107 A after the lock pin (not shown) is inserted into the chamber  105 A and recess  103 A in the spring holder  102 A. In alternate embodiments, the ram assembly may be operably held in the power section using any other suitable means. 
     It should be understood that the foregoing description is only illustrative of the invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.