Are you in the market for a used crane? Whether you are shopping online, in an auction setting, or through a private transaction, it is smart to have your mechanic or third-party inspector involved. Ask to see the inspection history of any previously owned crane you are seriously considering buying. You want to know that the machine has been well-maintained and has had regular, thorough annual inspections as required by OSHA 29 CFR1026.1400 and ANSI B30.5.
Annual crane inspections, and the discrepancies noted therein, are frequently the subject of controversy. This is due primarily to the difficulty in determining the degree of wear or damage on the moving components being examined and the tolerances for acceptable wear on those components. The more years the crane has been a “working machine”, the more “play” exists and the more difficult it becomes to determine what really is a hazard and what is not. These tolerances are frequently not published and can be difficult to obtain.
No reputable crane owner or broker wants to knowingly sell a crane with a structurally unsafe critical component. However, it can be very difficult for the used crane buyer to accurately determine the “for real” condition of the machine. Often, the challenge for your mechanic and/or inspector becomes identifying the difference between what presents a near-term hazard and what is showing wear but has not yet become a hazard but needs to be noted. Appropriately, OSHA CFR29, 1926.1400 and ANSI/ASME B30.5 offer little or no details or specifications in this regard, and they direct the owner to refer to “manufacturer’s specifications.”
All of the major crane manufacturers provide thorough inspection checklists offering the owner and inspector an opportunity to identify items which are not perfect but are also not yet unsafe. In addition to manufacturer-provided checklists and guidance, the Specialized Carriers & Rigging Association publishes an excellent set of generic inspection checklists, which represent a compilation of manufacturer-covered items as well as components determined over time in various types of cranes to be worthy of inspection.
After repairing accident-damaged used cranes, we frequently find areas of concern which either did not receive appropriate attention on previous inspections, or weren’t included on the inspection checklist and were therefore not noted. These missed items can and have contributed to component failure (sometimes catastrophic) and therefore directing attention to them is just smart business decision making.
Anyone who has been involved in crane operations or maintenance for more than a short time is aware that items such as booms; outrigger beams and boxes; hydraulic cylinders, hydraulic lines, hoses, and fittings; rotex and swing gears; pins; journals; sheaves; bearings; load lines; pendant lines; winches; load blocks; and lifting balls and hooks are among the many items critical to safe crane operations. As a used crane buyer, you want to know that this stuff is not excessively worn and works properly. Any reasonably-complete checklist will include these basic items and more with a space for noting “some attention needed.”
However, it is frequently difficult to determine acceptable limits of wear, play, or deflection in these and other crane components without defined tolerances. As those tolerances are seldom noted on checklists, following is a listing of our most common areas of concern. We insist on carefully inspecting and noting the current status of these areas prior to placing our company inspection placard on the crane. We recommend that the potential buyer obtain status data from the most recent inspection of these items before signing the contract:
1. Load Test: We insist on conducting a load test (not to exceed 110% maximum capacity) as part of every annual or recertification inspection. Keep the boom under load for an hour and you will frequently observe items which are not detectable in static conditions, such as:
a. Hydraulic lift cylinder, extend cylinder or outrigger cylinder bypassing, or leaking
b. Check valve(s) malfunctioning
c. Gland seals leaking
d. Hydraulic line and fitting leaks
e. Excessive boom deflection necessitating closer inspection of:
i. booms in high stress areas.
ii. cracked welds
iii. fatigued steel
iv. worn wear pads (when the boom “cocks” left or right or possibly up or down wear pads must be suspect)
f. Control valves bypassing
g. Winch “jerking” either up or down or in both functions
h. Load line fraying
2. Rotex gear: “Play” tolerance specification for a specific rotex gear is obtainable from either the crane or the bearing manufacturer.
a. On a hydraulic boom, with the outriggers fully out and down, lift the boom to a high boom angle and “jerk” the controls a bit. Repeat this step in the four quadrants and check the amount of play with a dial indicator or ruler, then compare amount of play to the crane specifications.
b. On a conventional boom, check bearing height relative to carrier surface in four quadrants. Lift and lower a load while checking the play. Rotate the turntable slowly 360° with a load on the boom.
c. If the crane had rolled over occasionally you’ll find excessive play or grinding when it passes the position it was in when it rolled over. This indicates the bearings damaged the race at that position and the gear needs to be replaced or refurbished.
3. High stress areas:
a. While under a load, closely examine the base boom section in the area just forward of the lift cylinder journal and the insert and point section(s), on the bottoms and sides in the area immediately after they exit from their parent component.
i. Look for signs of cracked paint, possible “spider web steel cracks,” cracked welds, steel deformation, and “bellying” in the area where the boom rests within the parent member when fully extended.
b. Check for excessive negative deflection in the fully extended boom
c. Check outrigger beams and boxes for similar damages at the same high stress locations.
I should note that during our 31 years of repairing damaged crane booms (over 10,000 booms) about half of them being hydraulic boom sections we almost always find that the cause of the boom or outrigger beam failure from overload started with the side plates “bellying” out and eventually the weld between the sides and bottom cap “blowing out” followed by catastrophic collapse. In many cases, the sidewall distortion was happening for an extended period of time prior to the boom failure and was detectable on close inspection.
4. Inspection of high wear areas:
a. Closely check for missing or badly worn slider pads and shims at the front and rear of each boom section and outrigger beam and box.
b. Under a load, check the base boom pivot pin, top and bottom lift cylinder pins, journals, and bushings. It is not unusual to find elongation of the pin hole well into or even through the bushing. This results in excessive boom “play” under operating conditions and contributes to accidents.
Over the course of many inspections, we have encountered discrepancies worthy of note and further investigation in all of the above referenced items. We encourage anyone involved in the business of maintaining high standards of maintenance in crane operations to incorporate these inspection methods into their used crane inspection procedure.
Doing so will prevent accidents and the resulting property damage, personal injury and potential loss of life.
Author: Michael D. Smith, Certified Boom Repair
Michael D. Smith is President and founder of Certified Boom Repair Service Inc., Tampa, Fla. Smith can be reached at firstname.lastname@example.org