DE1709401

1,209,318. Pile driving hammers. FMC CORP. 20 Nov., 1967 [2 Dec., 1966], No. 52664/67. Heading B3H. A diesel pile hammer has a free piston or ram 55 reciprocable in a cylinder 28, 29 and forming therewith a power chamber 50 within which gases are compressed during the downstroke of the ram and are subsequently supplied with fuel and ignited by fuel injection means 78, a scavenging chamber 53 connected by a conduit 70 with the power chamber and into which burnt gases are drawn during the upstroke of the ram, and means 95 for lifting the ram to its starting position. The lower surface of the piston 55 has a hemispherical cavity 73 which co-operates with a similar cavity 74 in an anvil 39 to form a combustion chamber 72, Fig. 1A, into which fuel is injected by a nozzle 78 supplied from a fuel injection pump 61, Fig. 11, actuated by a follower 60 engaged by a cam surface 59 on the falling ram 55. The quantity of fuel dispersed is controlled by remote means (130), Fig. 3A (not shown). The follower also actuates a lubricant pump (62). Anvil 39 is connected through cushion adapter plug 43, cushion 44 and driving head 42 with the pile 151. A pin 52 prevents rotation of the anvil. The larger diameter upper portion of the ram defines a bounce chamber 54, Fig. 11, communicating with an auxiliary bounce chamber 86 through port 81 which is closed by the ram upon excessive upward movement whereby the increase in pressure in the bounce chamber 54 provides rapid deceleration of the ram. During its subsequent downstroke under gravity assisted by the pressure in chamber 54 the ram causes the gases in scavenging chamber 53 to be discharged through conduit 70, ports 122, power chamber 50 and ports 77. When ports 122 are closed by the falling ram, a valve 126 opens to atmosphere. For both manoeuvring the hammer and lifting the ram to its starting position, a hoist rope 95, Fig. 1, passes around sheaves 117, 118 and is attached to a lifting mechanism 30, Fig. 2A (not shown), slidable in guides in the hammer and cooperating with an hydraulic damper (100), (103), Fig. 9 (not shown) for cushioning its downstroke. A rod 93 attached to mechanism 30 extends through a bush 89 and is adapted to engage a shoulder 90 on the ram for lifting it. A latch (98), Fig. 2A (not shown), actuated by a rope (99) is arranged to lock the mechanism 30 to the hammer to enable the latter to be positioned upon a pile by the lifting rope 95. In another embodiment, Figs. 16-21 (not shown), a one-way reed v