portant than the convenience of quickly changing
DEPLOYMENTS
out cutters. The system was assembled on the sur-
Funding difficulties delayed deployment in
face and tested against a mound of snow formed
Antarctica until January of 1996. During this de-
while trenching for the tunnel starting point (Fig.
ployment, the system was assembled and tested
17). Hydraulic oil heating problems again sur-
at the South Pole Station, modified, and an attempt
faced, and the guarding needed to be removed.
was made to begin tunneling operations. Equip-
The fan motor still lugged, albeit not as severely
ment failures brought operations to a close shortly
as at CRREL, but still enough to be of concern.
after starting. Following the January deployment,
Ramping up time for the motor was increased, and
we returned to the Pole in November and further
current limit was decreased at the soft-starter to
modified and tested the equipment. During this
try to reduce the strain on the motors. Some loss
deployment, the proof of concept tunnel, was
of control function experienced by the operator
completed. In January of 1998, the tunneler was
was worked around by actuating a blocked valve
flown to McMurdo where further modifications
(deadheading) to pressurize the control circuit
were made to improve the production rate of the
before activating the controls. Although this en-
system.
abled the operator to actuate the controls, it exac-
erbated the heating problems as the deadheaded
circuit vented through a pressure relief valve.
Initial deployment (199596 season)
In late 1995, four members of the design team
With system adjustments made, the tunneler
were approved for deployment by NSF to test the
and fan were lowered into the starting trench and
machine at the South Pole Station. A proof-of-con-
tunneling commenced. Shortly after starting, the
cept tunnel, originally planned for a length of 30
fan motor burned out. The motor was likely dam-
m at a depth of 11 m, was expanded to 125 m at a
aged at the Skiway in prior tests and finally gave
maximum depth of 16 m. It would also be a "work-
out during continuous running at the Pole. A call
ing tunnel," used for the station's wastewater sys-
was put in to McMurdo Station for a motor in the
tem.
30- to 37-kW range with the same motor frame
Prior to the start of surface tests, the equipment
size.
needed minor repairs due to damage caused dur-
Concurrently, problems developed with the
ing shipment. Loss of the cutters from the arms
flexible stainless steel hose used to direct chips
resulted in the decision to weld the cutters to the
from the snowblower to the ejector tube at the rear
seats, rather than bolting them in place. The in-
of the tunneler. Flexing of the hose led to repeated
tegrity of the assembly was considered more im-
breakage at the connection point. Attempts were
Figure 17. Surface testing of system.
15
Previous Page
