Resilient buffer device
United States Patent 1191 Fehl et al. Apr. 8, 1975 RESILIENT BUFFER DEVICE 3.293.224 15/191 36 oe Ment ..l 2174221 3,49 ,2 7 /l9 0 itzgerald eta. 93 l R [751 lnvemorsl &#39;E Wlhelmshaven? 3.494.607 2/1970 Rusch 293/71 R x wmfrled Helm, Accum bfllh of 3.690.710 9/1972 Curran... 293/71 R m y 3.7211433 3/1973 Sobel 293/1 [73] Assignee: Fried. Krupp Gesellschaft mit g r Haftung Essen A Primary E.\&#39;am1&#39;nerRobert S. Ward, Jr. ermmy Assistant Examiner-Howard Beltran [22] Filed: May 31, 1973 Almrney, Agent, or Firm-Walter Becker [211 App]. No.: 365,516  
 [30] Foreign Application Priority Data [57] ABSTRACT June Germany 2230130 A resilient buffer, especially for cranes, according to I which a buffer body consisting of foamed synthetic [52] 213/22! f% material is enclosed by a tight skin resistant to aggrcssive substances. The skin is formed by a prefabricated fig 252V? invelope which has that rim portion thereof which l 0 6 faces away from the impact surface of the buffer connected to a base plate.  
 [56] References Cited UNITED STATES PATENTS 5 Claims, 4 Drawmg Figures 324L875 3/l966 Staniland et al 2l3/22l I I I I I I I o I I RESILIENT BUFFER DEVICE The present invention relates to a buffer, especially for cranes, the buffer body of which is made of a foamed synthetic material and is surrounded by a tightskin resistance against aggressive substances. This skin, which heretofore was applied by spraying the respective synthetic material onto the foamed body is intended to protect the foamed material of the buffer body against aggressive substances such as gases and water steam. If the buffer body is formed by two or more sections cemented to each other, the skin is also intended to prevent a separation of said sections from each other or from the base plate of the buffer.  
  However, experience has shown that such sprayed on skin is not absolutely tight. It has been found that when preparing the skin, fine pores or passages cannot be completely avoided, particularly in the grooves which the buffer body has at the joints where the sections meet. It is through these pores and passages that air containing aggressive components enters the foamed body of the buffer body, particularly when the buffer body expands again after a compression and in this way, so to speak, breathes in the outer air through the pores and passages.  
  The harmful components or ingredients thus entering the foamed material bring about that the foamed body will after a while become rotten and is unable to meet its intended purpose any longer.  
  It is, therefore, an object of the present invention to provide a buffer, especially for cranes, in which the foamed body is reliably protected against harmful influences, and which buffer can be produced economically.  
  These and other objects and advantages of the invention will appear more clearly from the following specification, in connection with the accompanying drawings, in which:  
  FIGS. I and 2 respectively illustrate longitudinal sections through two embodiments of buffers according to the present invention.  
  FIGS. 3 and 4 respectively illustrate axial sections through portions of buffers according to two further embodiments of the invention.  
  Referring now to the drawings in detail, the buffer body is in all embodiments illustrated formed by three sections 1, 2, 3 of foamed synthetic material, for instance, of cellular polyurethane. The cells are preferably non-permeable and contain gas bubbles. Accordingly, the buffer body has a speed dependent characteristic which means that the buffer forces are all the greater the higher the speed is at which the buffer bodies are compressed. The section 1 is cemented to a base plate 4 and additionally is positively connected thereto by rivet-shaped extensions 5 which extend through and fully fill corresponding bores in the base plate 4 which is realized by the foaming process when producing the section 1. The ends of the extensions 5 are widened in a truncated cone-shaped manner.  
  According to the embodiment of FIG. 1, a prefabricated sleeve or envelope 6 which consists of a strong synthetic material resistant against aggressive substances is in a tight and taut manner pulled over the buffer body 1, 2, 3. This sleeve 6 tightly engages the impact surface 7 as well as the circumferential surface of the buffer body and has no pores or passages so that the buffer body is tightly closed off on all sides. The sleeve 6 has that rim portion which faces away from the impact surface 7 provided with a collar 8 which rests on the base plate 4. The collar 8 is pressed against the base plate 4 by means of a flat ring 9 and screws 10. Screws 10, the heads of which are countersunk in ring 9 pass through bores in the collar 8 and are screwed into threaded bores of the base plate 4. The marginal portions of the ring 9 are rounded at E so that the sleeve 6 will not be damaged when the sleeve 6 widens during a compression of the buffer body. Collar 8 may be connected to the base plate 5 by cementing, or the like. If desired, this connection may be effected by cementing as well as by pressing the collar onto the plate 4, for instance, by means of a ring 9 and screws 10.  
  Since in this way the sleeve 6 is firmly adhering to the base plate 4, the sleeve 6 will always meet its require ment, namely, to firmly hold the sections l, 2 and 3 of the synthetic body together.  
  According to the embodiments of FIGS. 2, 3 and 4, the sleeve or envelope 11 is connected to the base plate 4 by pulling that rim of the sleeve which faces away from the impact surface 7 of the buffer body into an annular groove on the base plate 4.  
  According to the embodiment of FIG. 2, the annular groove 12 is provided in a cylindrical extension 13 of the base plate 4 against which the disc I of the buffer body rests and which has the same diameter as disc I. The annular groove 12 is so arranged that the outer surface 14 of the base plate 4 continues without step into the annular groove 12.  
  The rim 15 of sleeve 11 is pulled tightly into the annular groove I2 by heating the sleeve 11 after it has been loosely pulled over the body 1, 2, 3 of synthetic material. In view of the heating up of sleeve 11, the latter shrinks so that it tightly engages the buffer body. Consequently, the nubs 16 located at the impact surface 7 of the buffer body protrude from the sleeve II which tightly surrounds the same so that they can meet their requirements, namely, during a slant buffer shock to prevent the counterbody from sliding off. Also in radial direction, the sleeve II will when being heated up, tightly engage the buffer body 1, 2, 3. The sleeve 1] is pulled into annular grooves 17 between each two discs I, 2 and 2, 3. The rim 15 of the sleeve 11 which first forms the continuation of the cylindrical parts of sleeve 11 as illustred in FIG. 2 by dot-dash line I5 is, in view of the shrinking brought about by the heating up of sleeve ll pulled into the annular groove 12 as is shown in FIG. 2 with solid lines. The rim 15 will thus under tension be located in the annular groove 12 and will firmly clamp the sleeve 11 against the base plate 4. Accordingly, the sleeve 11 will be able firmly to hold the sections 1, 2, 3 of the buffer body against the base plate 4.  
  Preferably, a skin of synthetic material may be sprayed over the rim of sleeve 11; this rim is pulled into the annular groove 12 and also over the adjacent region of the outer surface 14 of base plate 4 so that a particularly firm and tight connection will be obtained between the rim 15 and the base plate 4.  
  The embodiment of FIG. 3 differs from that of FIG. 2 merely in that the annular groove 18 is not worked into the extension 13 of base plate 1, but is formed by having section 1 protrude in radial direction relative to the circumferential surface of extension 13. Also, in this instance, the rim 15 of the sleeve 11 is pulled into groove l8 by the fact that in view of the heating of sleeve 11 a shrinking thereof is effected.  
  According to the embodiment of FIG. 4, the annular groove 19 is formed by having the section 1 spring back in a range extending up to the base plate 4 and all the way around. In this instance, the base plate 4 does not have the extension 13 of FIG. 3. Also, in this instance, by heating the sleeve 11 and the shrinking of sleeve 11 inherent thereto, the sleeve 11 will on all sides tightly engage the buffer body and its rim 15 will be pulled into the annular groove 19. FIG. 4 further shows that also in this instance the sleeve ll is pulled into the annular groove 17 which is located at the joint between the sections 1 and 2. Furthermore, it will be seen from FIG. 4 that a sprayed-on skin 21 extends over the rim 15 of sleeve 11, which rim is pulled into the annular groove 19 and extends in particular over a lip 20 of rim 15 which lip engages the base plate 4. The skin 21 continues over the outer surface 14 of the base plate 4. In this way a tight adherence of the rim 15 to the base plate 4 will be realized.  
  The required tight engagement of the body 1, 2, 3 of synthetic material by the sleeve 6, 11 may, if desired, also be realized by inserting the prefabricated sleeve prior to the manufacture of the buffer body into a foam mold so that the said sleeve will first have an outer diameter which is less than the inner diameter of the mold while also the plane closure part of the sleeve which is tightly to engage the impact surface 7 of the buffer body will first be spaced from the bottom of the mold. Thereupon, the synthetic material is foamed within the sleeve 6, 11. During this foaming operation, the foam being formed swells over the volume enclosed by the sleeve. As a result thereof, the sleeve is widened until it engages the cylindrical inner wall as well as the bottom of said mold. In view of this widening of the sleeve, the required tight engagement of the sleeve with the finished foamed buffer body is realized. This method can be employed in particular with the embodiment of FIG. 4 when the sleeve 11 is inserted into such mold first in radially spaced relationship thereto, said mold having annular strips corresponding to the annular grooves 17 and 19.  
  It is, of course, to be understood that the present in vention is, by no means, limited to the specific showing in the drawings, but also comprises any modifications within the scope of the appended claims.  
 What we claim is:  
  l. A buffer, especially for cranes, which includes: a buffer body of foamed synthetic material, a base plate supporting said buffer body and being connected thereto, and a pre-fabricated fluid-tight protective envelope engaging and encasing said buffer body and being firmly connected to said base plate, said base plate having perforations, and said buffer body having extension means extending into said perforations and being anchored therein, said base plate having a reduced diameter section surrounded by a portion of said envelope, and said reduced diameter section being provided with a circumferential groove having the adjacent envelope portion firmly anchored therein.  
  2. A buffer according to claim 1, in which the reduced diameter section of said base plate corresponds in cross section substantially to that of the adjacent buffer portion.  
  3. A buffer, especially for cranes, which includes: a buffer body of foamed synthetic material, a base plate supporting said buffer body and being connected thereto, and a pre-fabricated fluid-tight protective envelope engaging and encasing said buffer body and being firmly connected to said base plate, said base plate having perforations, and said buffer body having extension means extending into said perforations and being anchored therein, said base plate having a reduced diameter section with the diameter thereof less than the diameter of the adjacent buffer section whereby a groove is formed in part by the circumferential surface of said reduced diameter section and in part by the adjacent surface of the remainder of said base plate and in part by the adjacent surface of said buffer body, said envelope having that portion thereof which is adjacent said last mentioned groove nesting and an chored in the latter.  
  4. A buffer, especially for cranes, which includes: a buffer body of foamed synthetic material, a base plate supporting said buffer body and being connected thereto, and a pre-fabricated fluid-tight protective envelope engaging and encasing said buffer body and being firmly connected to said base plate, said base plate having perforations, and said buffer body having extension means extending into said perforations and being anchored therein, said buffer body having a reduced diameter portion directly adjacent said base plate forming a spring back section with the major por tion of said buffer body, said section together with an adjacent portion of said base plate forming a circumferential groove receiving and having anchored therein the adjacent portion of said envelope.  
  5. A buffer according to claim 4, which includes a skin over an end portion of the envelope in said last mentioned circumferential groove and an adjacent surface portion of said base plate.