The present disclosure relates to hydraulic hammers and, more particularly, relates to a system and method for easy removal of lower bushings of hydraulic hammers.
Hydraulic hammers are widely used on work sites to break up or demolish large hard objects, such as, rocks, concrete, asphalt, frozen ground, etc., before such objects can be moved away. Hydraulic hammers can be mounted to work machines like back hoes or excavators, or they can be hand-held. In operation, high pressure fluid drives a piston of the hydraulic hammer to strike a work tool, such as a tool bit, which then strikes the hard object to be broken.
Generally speaking, the work tool is retained within a lower and an upper bushing of the hydraulic hammer, and the upper and the lower bushings in turn are enclosed within a bore of a sleeve or housing, also commonly referred to as a front head. Because of repeated impact of the work tool on hard objects, the lower bushing of the hydraulic hammer experiences extreme loads during operation. Such extreme loads often cause the lower bushing to wear out. As such, the lower bushing may need to be replaced or serviced several times during the product life of the hydraulic hammer. In order to remove the lower bushing from the front head, a cross pin connecting the front head and the lower bushing together may be detached and, the lower bushing may be pulled or pushed out from the front head for replacement or for servicing.
Conventionally, the outer surface of the lower bushing and an inner surface of the bore of the front head are designed parallel to each other such that when the lower bushing is pushed (or pulled) out for removal from the front head, the clearance between the lower bushing and the front head remains the same until the lower bushing is completely removed from the front head bore. As this clearance is small, contact between the lower bushing and the front head may occur, thereby making the removal of the lower bushing difficult. In certain instances, the lower bushing may change its shape during usage, causing the surfaces of the lower bushing and the front head to bind during removal, thereby exacerbating the removal process of the lower bushing. This difficulty in removing the lower bushing from the front head not only increases the servicing time of the lower bushing, it also adds to the labor cost and may even corrode the front head somewhat, which in turn may lead to replacement of the hydraulic hammer altogether.
It would accordingly be beneficial if an improved mechanism for effectively removing the lower bushing from the front head were developed. It would additionally be beneficial if such a mechanism avoided contact between the front head and the lower bushing during removal.
In accordance with one aspect of the present disclosure, a hydraulic hammer is disclosed. The hydraulic hammer may include a front head defining a bore therein, an inner surface of the bore having a first taper and, a lower bushing capable of being positioned within the bore, an outer surface of the lower bushing having a second taper, the first taper substantially following the second taper.
In accordance with another aspect of the present disclosure, a lower bushing is disclosed. The lower bushing may include an outer wall and an inner wall. The inner wall may define a bore therein and the outer wall may have a tapered surface such that the outer wall and the inner wall are non-parallel to one another.
In accordance with yet another aspect of the present disclosure, a method of removing a lower bushing from a front head of a hydraulic hammer is disclosed. The method may include providing (a) a front head defining a bore therein, the bore having an inner surface with a first taper; and (b) a lower bushing capable of being positioned within the bore, the lower bushing having an outer surface with a second taper and, the inner surface of the bore and the outer surface of the lower bushing defining a clearance therebetween, the clearance remaining constant in an installed state of the lower bushing. The method may also include removing the lower bushing from the front head by increasing the clearance as the lower bushing extends out of the front head.
While the present disclosure is susceptible to various modifications and alternative constructions, certain illustrative embodiments thereof, will be shown and described below in detail. It should be understood, however, that there is no intention to be limited to the specific embodiments disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents along within the spirit and scope of the present disclosure.
The present disclosure provides a system and method to effectively remove a lower bushing from a front head of a hydraulic hammer. In this respect and referring to
It will be understood that only those components that are essential for a proper understanding of the present disclosure are shown and/or described herein. Nevertheless, several other components that are commonly employed in combination or conjunction with the work machine 2 and the hydraulic hammer 4 are contemplated and considered within the scope of the present disclosure.
Turning now to
Notwithstanding the components of the hydraulic hammer 4 described above, it will be understood that several other components that have not been described, such as, various pins and retainers for retaining the upper bushing 30 and the work tool 8 within the front head 12 and for connecting those components relative to one another and the lower bushing 28, various sealing rings, etc. are contemplated and considered within the scope of the present disclosure.
Referring now to
In order to facilitate an effective removal of the lower bushing 28 from the front head 12, each of the lower bushing 28 and the front head 12 may be provided with a tapered surface. With respect to the lower bushing 28 in particular, an outer surface (or wall) 34 of the lower bushing may be tapered (e.g., have a conical or substantially conical surface) and the tapering may extend along an entire (or substantially entire) length of the lower bushing. In at least some embodiments, the outer surface 34 may be tapered by an angle Θ (See.
Furthermore, the tapered lower bushing 28 may be tightly held and fitted within the similarly tapered bore 14 of the front head 12. Specifically, the length of the bore 14 of the front head 12 that may be in contact with the outer surface 34 of the lower bushing 28 during a normal installed state may be tapered in at least some embodiments. The degree of tapering of the bore 14 may be similar to the degree of tapering of the outer surface 34 of the lower bushing 28. Thus, in at least some embodiments, the bore 14 and, particularly, an inner surface 35 of the bore, may be tapered by an angle Θ′ of about half a degree to about one degree relative to a vertical surface or line 42 and may have a broader bottom bore portion 44 and a narrower top bore portion 46 to mimic the broader bottom portion 38 and the narrower top portion 40, respectively, of the lower bushing 28.
By virtue of designing the lower bushing 28 and the bore 14 of the front head 12 with tapered surfaces, easy removal of the lower bushing from the front head may be facilitated. Specifically, due to the tapering of the lower bushing 28 and the front head 12, a clearance (e.g., the gap between the front head and the lower bushing) 47 may increase as the lower bushing is pulled (or pushed) out from the front head for servicing or replacement. This increase in the clearance 47 between the lower bushing 28 and the front head 12 as the lower bushing is removed from the front head may prevent any contact between the lower bushing and the front head even when the shape of the outer surface 34 of the lower bushing changes during usage, thereby making the removal of the lower bushing easy.
Furthermore, during removal of the lower bushing 28 from the front head 12, the lower bushing may only need to be pulled (or pushed) by a small distance D (See.
Thus, as the lower bushing 28 is removed from the bore 14 of the front head 12, the clearance 47 between the lower bushing and the front head gradually increases. An exemplary increase in the amount of the clearance 47 as the lower bushing 28 is removed from the front head 12 is shown in a tabular form in
Referring now to
As shown in
These measurements are in contrast to the measurements shown in
Turning now to
In particular, the lower bushing 28 may include the outer wall 34 and an inner wall 78, the inner wall defining a bore 80 within which the work tool 8 may be received and secured. Furthermore, as described above, and as clearly shown in
Additionally, the outer wall 34 may include a plurality of elongated recesses 82, positioned at (or substantially at) ninety degrees to one another. Any one of the recesses 82 may be employed for inserting the cross-pins 32 to secure the lower bushing 28 to the front head 12. Typically, only one of the cross-pins 32, and thus, only one of the recesses 82 is used for securing the front head 12 and the lower bushing 28. However, since wear on the inner surface (e.g., the inner wall 78) of the lower bushing 28 may not be even (the front and the back inner surfaces may wear more than the side surfaces, or vice-versa), the lower bushing may be rotated by ninety degrees (and the recess 82 at that ninety degree angle may be used to secure the front head 12 and the lower bushing) to extend the operating life of the lower bushing before replacement may be needed.
The outer wall 34 may further include one or more chamfered or circumferential grooves 84 flanked on either sides by additional grooves (e.g., square grooves) 86. The chamfered grooves 84 may be employed for receiving lubricant from the front head 12 and for supplying that lubricant (e.g., grease) to lubricate the surface between the inner wall 78 and the work tool 8. Specifically, the lubricant received from the front head 12 may fill around the chamfered grooves 84 and may then flow to the surface of the inner wall 78 by way of a plurality (e.g., four apertures) of apertures 88. The additional grooves 86 may be employed for holding sealing mechanisms (such as, O-rings) for containing the lubricant within the chamfered grooves 84, thereby preventing the lubricant from flowing along the outer wall 34 of the lower bushing 28.
Notwithstanding the features of the lower bushing 28 described above with respect to
In general, the present disclosure sets forth a system and method for easily removing a lower bushing from a front head of a hydraulic hammer for replacement or servicing. One or both of the front head and the lower bushing may have a tapered or otherwise conical (or substantially conical and tapered) configuration. Specifically, an outer surface of the lower bushing may be tapered and an inner bore surface of the front head may be tapered as well mimicking the taper of the lower bushing. A method of removing the lower bushing from the front head is shown in the flowchart of
Referring to
By virtue of providing the tapered surfaces of the lower bushing and the front head bore, and by mimicking the tapering of those surfaces, the clearance between those surfaces remain the same as the conventional design during a working assembly, and the clearance increases only as the lower bushing is pushed out for replacement or servicing, thereby making the removal of the lower bushing easy. Easing the removal of the lower bushing not only saves time and labor cost, it also prevents the inadvertent damage of the front head (that may occur due to binding of the front head and the lower bushing), thereby preventing a complete replacement of the hydraulic hammer.
While only certain embodiments have been set forth, alternatives and modifications will be apparent from the above description to those skilled in the art. These and other alternatives are considered equivalents and within the spirit and scope of this disclosure and the appended claims.