|Direction lever shown in the
Down position. When lifted so that the notch is
engaged it's in the UP position.
Important: The jack must be loaded with a minimum of 110 lbs. to lower step-by-step, otherwise the lifting nose will drop.
|You can see tht the hand
grip (black) is 6-5/8" from the axle. The highest
leverage is when there's only
enough strap on the axle in order to prevent slipage, a radius of 3/4". The mechanical advantage is about 9 to 1, so a 50 lbs pull on the handle would result in about 450 lbs tension in the strap.
There are 10 notches on the ratchet wheel so the handle travels 4.1" per notch.
|There are two ratchet
wheels, one on each side of the axle. There's a
handle pawl and a load pawl.
Once there's some tension on the strap the load pawl can not be retracted unless the handle is pulled enough to unload the load pawl.
When starting out pass the strap through the slot in the axle and pull the strap so it's tight. Then just work the handle and after a half turn or so the strap will bind to the axle and then the handle will tension the strap.
|In this configuration 2 &
single strap the force is just what the ratchet can apply.
Not enough to move the empty container.
But when a steel TV mast is used to add tension to the strap the
container moves a little less than in inch.
|In this configuration 2 &
doubled strap, the force is doubled, but the empty
still will not move just from the ratchet force.
Now when the TV mast is used it takes less effort to move
Maybe an extension on the ratchet handle would move the container?
ans: The release lever is in the way of just using a pry bar.
Also the mast should be pulling only one strap to double it's effectiveness.
Yes, pulling on just one strap doubles the effect.
Container now moved about a foot closer.
|If the jack is used at the
top to try and pull
the container, it causes the lower left edge
to dig into the ground. NOT GOOD.
|When a strap is used from
the upper left of the full
container to the lower left of the empty container the
forces not only moves the empty container on the right
to the left it also takes weight off the lower left edge.
|When the jack is used
between the lower right of the full
container and the lower left of the empty container not only
is the empty container moved to the left but also some
weight is taken off the lower left edge. Good
But the jack top jaw slipps out.
||Tried this but the top jaw
rotated because the small tab broke off.
Because of the rotation when you try to clamp the jaw slips off, so it's useless now.
The design problem is that the there's a gap to the right of the I-beam and the top jaw that allows this rotation. This is why you see many of these jacks offered for sale without the top jaw.
Looped a 3' Class III Safety Towing Chain through the lower left hole in the empty container and hooked the jack lower jaw in the lower right hole of the full container, configuration 3 (above).
This worked for about 3 cycles then the jack handle broke at it's base because I was not pulling exactly in the plane of the handle motion.
6772488 Wire spring latch safety hook
|The nut that holds the top
jaw on the jack has loosened and needs to be
tightened. In addition to the lock washer I'll add
some weak locktite.
After fixing the top jaw and starting to pull the front toghther, two problems showed up:
1) as the front moves closer the rear seperates. It would be good to use the strap wrench to hold one end as the other end is moved.
2) the flange on one side of the top jaw broke off allowing the top jaw to turn, not good. You can see crystalized metal at the break, i.e. it's cast metal. The thing to do is have a new top jaw made of steel instead of a casting.
|This suggests two imporved
1) a stronger top jaw.
2) an improved handle.
3) better retaining method for handle pivot pin
|The top clamp can be
installed pointing up. Then the hole in the clamp
can be for a hook on some supporting cable. The long
side is flush when in the up position.
I'm going to take this one back and add a new longer bolt to replace the 42mm long x 12mm dia. - 1.75mm pitch bolt so that malleable iron washers can be used on both sides. Also going to grind the top jaw so it fits properly into the I-beam. Maybe a 1/2" bolt?
|After a lot of filing &
grinding interspersed with an application of machinist's
blue there's no tendency to climb and the side toward the
teeth is now touching the I-beam (before that was a 0.050"
gap along that side.
|The Top Jow pointing
Up. The jack could be lifted by a crane. Also
a sleeve could pass over the top jaw,, like shown in the
Pole Setting device patent.
As received the top jaw would not fit because the "tabs" were too big.
|The chain hoist can lift up
Note: the force of the chain (see Configurations above)
is primarily up with a small force pulling the container to
the left. But pushing the right side of the container will
not budge it at all. This suggests that there's an optimum
angle that will have enough lift and also enough sideways
force to move the container.
The tare weight is 5,300 pounds.
|Tow Chain with Grab Hooks
5/16" x 20' Grade 70 Yellow Zinc
Home Depot Model # 00422 Store SKU # 529425
|20' Log Chain at upper
3' Class III towing safety chain upper right
||The log chain has hooks on
both ends that are designed to
hook onto the chain. You can also buy another hook that
can be inserted into any link. This should allow getting any
desired angle of pull.
|More shallow angle on chain.
||1/4" Grab Hook added to Tow
Home Depot Model # CH8001-6 Store SKU # 566678
Note the hook is installed at the end of a link. It will not fit in the center of a link.
|5/16" Grab Hook
||5/16" Support (SUP) Hook
|5/16"' Chain Grab Hook Fitted
to 5/16" Tow Chain
page created 30 Sep 2011.