SWDM40 OPERATION & MAINTENANCE MANUAL
Five: It’s forbidden to loosen main winch excessively.
If main winch rope is loosened excessively, the elevator will fall. After Kelly rotates, elevator
and flat head will deform and break, even cut off the wire rope.
Six: It’s forbidden to place Rotary drive too high or too low when throwing soil.
Rotary drive too low will cause incomplete contact of inner spline and Kelly key bar on which
impact increased partly and leading the crack of key bar or lower pipe.
Rotary drive too high will cause excessive impact for outer lower crowd block while throwing
soil breaking Kelly and damaging Rotary drive.
Seven: It’s forbidden to use the Kelly to press pile casing, stir soil, and mix slurry.
Because these operations may make Kelly core bar to bear force partly, resulting in the crack
or break-off near the junction position of square head and core bar steel pipe.
Eight: It’s forbidden to operate with unsuitable Kelly and drill bit.
An open bucket (two half bucket) should be used when the hole diameter is small or soil
viscidity is high. The type of Kelly is precise for a small piling hole. Thus, it’s forbidden to
install a small drill bit onto the Kelly resulting in outer Kelly scratching on the hole wall.
Nine: It’s forbidden to drill too deep with a single bucket.
For a piling hole with small diameter or a auger bit, too deep drilling over than spring seat may
result in Kelly stuck caused by soil squeezed into the gap for a long time.
Ten: It’s forbidden to swing the upper-carriage with the bucket door open.
Avoid the crack, deformation and break-off caused by the collision of track and bucket door.
7.1.3.3 Cause and Prevention for Followed and Smashed Kelly
Followed Kelly:
When retraction, the fourth section retracts completely, collide and nod, at this moment
somewhere of the third section stuck at the second section which is driven to move up in
advance, this is called as followed Kelly. At this time, nodding also happens. If followed Kelly
is not found at once and lifted to a certain height, the stuck position will be loosened caused by
shock or collision, the second Kelly will be dropped to collide the disc or on the inner spline of
the first section drive sleeve, this is called as smashed Kelly, which may result in positioning
ring damage, bulge of drive sleeve, Kelly lock, Rotary drive falling and even Kelly falling into
the hole caused by rope breakoff.
Prevention Measurements
1. Operator should know the crowd length of outer rod of Kelly and inner rod of each section,
remember the piling depth for the position of pressurization and machine nodding depth caused
by lifted disc colliding with drive sleeve of each section.
2. When nodding at abnormal depth, operator should lift Rotary drive slowly till fitting with the
Kelly absorber to prevent Rotary drive falling down, and then rotate anticlockwise to lower the
Kelly and loosen it out completely, and retract the Kelly again.
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