On-site machining of a fan shaft for one of the main ventilation fans of the N.Y.C. Lincoln Tunnel

Problem:

A 5" I.D. double roller bearing of one of the main fans that supplies air to the N.Y.C's Lincoln tunnel failed due to the accidental drainage of the oil reservoir. The failure wasn't discovered until hours later during a schedule maintenance check.

By this time the 5" shaft of this huge fan that weighs several tons, got so badly scored and so hot that according to the in house maintenance people, did not "cool off" until the next day. In addition, to the badly scored journal area, the intense heat and the considerable "pull" of the (6) six belt, 48" diameter sheave had caused the shaft to bend at the journal area creating a .120" total run out at the end of the shaft. For all practical purposes and until a feasible solution could be found, this fan was out of commission.

Possible Solutions:

  • Removal of the fan cage/shaft assembly for transportation to a shop where the shaft could be repaired or replaced. Clearly a major rigging operation, a very costly repair job and several weeks of down time.
  • Attempting to remove the shaft from the fan cage without dismantling the fan housing. A tough and lengthy process that in no way would assure the successful removal of the shaft and could actually cause more damage to the entire unit.

Frontline’s Solution:

  1. On site machining of the journal area just enough to achieve a clean and true surface.
  2. Heat shrink a stainless steel sleeve long enough to cover the entire journal area.
  3. Secure sleeve to shaft by means of key and pin.
  4. Machine and grind sleeve to achieve a true surface to within .001" of bearing tolerance.
  5. Machine end of shaft to eliminate "run out".
  6. Re-cut key way to standard size.
  7. Machine I.D. of a sheave bushing to the new shaft size.
  8. Install new bearing.
  9. Put fan back into operation.

All this was done by Frontline using only a (2) two man field crew in just (2) two days and at a nominal cost.

Click on the images below to enlarge

Fan, right after having
removed failed bearing.
Badly scored
bearing journal.
Machining of
damaged area.
Shrink fitting of a sleeve
and initial machining.
Final machining of sleeve
and of shaft end.
Bearing mounted in place.

The Results Were:

  1. A repair as permanent as a new shaft.
  2. A very low repair cost.
  3. A very short down time.
  4. A very happy customer.

Once again the people at Frontline proved their total commitment to excellence and quality service by completing a job that would normally be considered a nightmare.

Copyright ©2007 Frontline Industries, Inc. All Rights Reserved.