The drilling shaft 8 is tubular. Accordingly, a channel 78 extends through the drilling shaft 8 all the way from an inlet in the end of the rear section 57 of the drilling shaft, which projects into the annular water chamber 82 in the area of the cylindrical projection 50 that accordingly also projects into the annular water chamber 82, more precisely in the upper part of the water chamber at a level above the axis of rotation of the motor shaft 16. The oval annular shape of the water chamber 82-more precisely essentially an "oval torus shape"-has also in this connection relevance to a beneficial constructional design, in that the water can be led directly into the through channel 78 in the drilling shaft, from the upper part of the water chamber 82 not far from the upper side of the drilling machine, where it is desirable also for the drilling shaft to be positioned. Initially, the water channel 78 in the drilling shaft 8 has a relatively small cross-section in the area of the rearmost section 57 of the drilling shaft, but it widens gradually as the diameter of the drilling shaft increases stepwise in the area of the transmission 22.

  A leakage of water and/or oil in the area of the rearmost section 57 of the drilling shaft is counteracted by the rearmost section 57 of the drilling shaft being small in diameter, which means that also the peripheral speed of the shaft is correspondingly low in this area, something that facilitates the sealing and/or prolongs the life span of the sealing. According to the embodiment there are two radial lip seals in this area; Said second radial lip seal 91 extends to the edge of the cylindrical projection 50. The first radial lip seal 90 should primarily prevent oil from leaking backwards along the drilling shaft, while the second radial lip seal 91 should stop water from leaving the water chamber 82 along the drilling shaft. These terms can be fulfilled by the problem solution according to the invention, implying among other things that the sealing is made in a section of the drilling shaft where the diameter of the shaft is small. For safety reasons, there is however arranged a telltale channel 92 that extends from the parting line between the radial lip seals 90, 91, to the outside of the machine, where it is easy to see on the upper side of the machine, for detection of possible water and/or oil leakage.

  The assembled drilling machine 1 contains two additional radial lip seals. In the front part of the gear box housing 20, in the front unit 4, there is a radial lip seal 94 that seals against the drilling shaft 8 between the transmission 22 and a front, sturdy ball bearing 95 on the outgoing drilling shaft, where it has a considerably larger diameter than in its rearmost section 57.

 On the motor shaft 16, in front of the ball bearing 75, there is a radial seal 96 that prevents oil from leaking from the gear box housing 20 and into the fan chamber 79. Thus, the only radial lip seals in the assembled drilling machine 1 that abut against moving machine parts and that seal against water leakage, are the radial lip seals 91 and 90, primarily said second radial seal 91 on the rearmost section 57 of the drilling shaft having a small diameter and hence a low peripheral speed of the drilling shaft. Both of these two seals are easy to access by detaching the rear and front units 2 and 4, respectively, from each other, which is easy to accomplish by unfastening the screw joints that keep the two units together. Hence, changing of the first and second radial lip seals 90, 91 does not require any extensive disassembly, since the rear unit 2 as well as the front unit 4 can remain intact during such maintenance.

 [0054] O-rings are used to seal between stationary machine elements in the drilling machine 1. Accordingly, a first O-ring 100 is provided to prevent water leakage between the motor housing end cover 18 and the gear housing end cover 21. More precisely, the O-ring 100 is arranged between said fourth shelf 63 on the motor housing end cover 18 and said first shelf 45 on the gear housing end cover. A second O-ring, for preventing water or oil leakage, is arranged in an annular groove 73 in said sixth wall portion 68 of the motor housing end cover 18, sealingly against the through hole 53 in the gear housing end cover 21. A third O-ring is arranged in an annular groove 88 in the gear housing end cover 21, to prevent water leakage from the channel 84 in the parting line between the gear box housing 20 and the gear housing end cover 21. A fourth O-ring 103 is arranged in a groove 89 in the gear housing end cover 21 in order to seal between the gear housing end cover 21 and the inside of the gear box housing wall. 钻孔机英文文献和中文翻译(6):http://www.751com.cn/fanyi/lunwen_56212.html