12
AP Dynamometer Service Manual
Wear of shackles
Shackles showing a wear reduction due to use that reduces any nominal
dimension of the shackle by five percent (5%) or pin by more than 2.5
percent (2.5%) shall be permanently removed from service.
For units up to 20,000 lbs, shackle pins found to have needle bearing
impression marks not greater than 0.004 inch deep are acceptable provided
the dynamometer calibrates satisfactorily. If the impression marks are
greater than 0.004 inch deep, the pin shall be permanently removed from
service.
Deformation of shackles
Shackles that are determined to have been deformed (aside from local
distortion at contact sites) shall be permanently removed from service. Any
visually apparent bending or twisting out of the natural plane of the shackle
or any distortion of nominal shackle profile (beyond the localized wear found
at the shackle loading point) is cause for permanent removal from service
Any shackles or pins that have a combination of wear and ground out areas
that exceed the above stated percentages should be removed from service.
Repair by means of welding is prohibited.
You may remove small defects from Dillon shackle assembles by grinding
but care must be taken to keep the removal of material to a minimum. This
section gives you guidelines on this procedure.
You may grind the following Dillon shackle assemblies:
• P/N 30010-0013—Anchor shackle
• P/N 33202-0015—up to 15,000 lb oversize
• P/N 33202-0023—20,000 lb 5:1 oversized
• P/N 30371-0016—30,000 lb through 50,000 lb standard
• P/N 30332-0014—100,000 lb
Discontinuities that run parallel to the contour of the shackle or pin are
usually not serious and do not need removal. Discontinuities that are trans-
verse to the contour of the shackle or pin are more serious and may reduce
longevity of the shackle or pin. Items with apparent cracks in any direction
should be removed from service immediately.
Discontinuities may be removed by grinding longitudinally following the
contour of the shackle or pin producing a smooth undulating surface. The
ground area must have a smooth blended transition with adjacent surfaces
and a minimum taper of 3:1. No more than 0.06 inches (1.5mm) of material
should be removed in depth and should not reduce any nominal dimension
of the shackle by five percent (5%) or pin by more than 2.5 percent (2.5%).
Grinding in the roller-bearing contact area of the shackle pin is not
authorized, as a smooth and round surface is required for proper
dynamometer performance. Re-inspection is required after grinding to
determine if the original discontinuities were relevant.
Shackles showing a wear reduction due to use that reduces any nominal
dimension by more than 5% or the pin by more than 2.5% shall be perma-
nently removed from service.
Inspection of the
Shackles and Pins
Defect Removal
Allowances for
Shackles and Shackle
Pins
After grinding, apply suitable
corrosion protection to the
shackles.
The shackles and pins that are
supplied with the AP dyna-
mometer are produced to tight
tolerances to mate with the AP
components in order to main-
tain the accuracy specifications
of the instrument. Substitution,
elimination or improper re-
placement of these compo-
nents can result in substandard
performance and possible
safety issues.
The maximum cross sectional
area reductions for the shack-
les and shackle pins are 10%
and 5% respectively. The
nominal dimension removal
allowances noted above will
insure that the cross sectional
areas remain within permis-
sible range.
