181 Chapter 9 Nonstructural Panel Repair
Copyright Goodheart-Willcox Co., Inc.
As we already know, a force will always move the
weakest object. When the force is acting upon two
or more objects (as with the come-along setup), the
weakest object will move first. If the attachment to the
vehicle is weak, it will give first. If the anchoring point
is weakest, the anchor will give way. If the attachment
and anchor are stronger than the damage, the damage
will move first.
Figure 9-18 shows a hydraulic ram being used to
pull out damage. The vehicle is anchored so it cannot
move. Likewise, the hydraulic ram cannot move. As the
chain is tightened between the vehicle and the ram, the
damaged area will move, lengthening the panel.
The immobilizing position is important. Remember
that a corrective pull will always try to make a straight
line between the attachment and the pull. In most cases,
a straight out pull is needed. This means that the pull
should be at the same height as the attachment.
W W W W W W O O O O O O R R R R R R K K K K K K I I I I I I N N N N N N G G G G G G S S S S S S M M M M M M A A A A A A R R R R R R T T T T T T
A As As As ten t t t en en ion si si si on on is i i i s s ap ap ap li pl pl pl ie ie ie d d d d t to to to an a a n n an an an hor ch ch ch or or d ed ed ed
vehi ve hi hi le cl cl e, th t t he he suspensi s us pe ns io io n n may ma y sag sa g. To T T o
prevent this load on the suspension,
b oc u de e e o inse se rt b lo cking g un de r the e ve hic cl e to
maintain vehicle height. Blocking will
keep the vehicle at the proper height so the pull will
work as intended.
Pushing
Pushing with a four-ton hydraulic power set applies
a constant corrective force to align damaged panels.
For example, in a unibody vehicle that has been hit in
the rear, the power set can be positioned in the trunk
to push out the damaged rear body panel and quarter
panel. If a quarter panel has been hit from the side and
is shortened in length, the power set can be positioned
inside the trunk to push the quarter panel to proper
length, causing lift reaction to remove the damage.
The power set ram requires a strong base. The
force created by the ram not only pushes on the
damage, but it pushes on the base as well. Remember
that when force is applied, the weakest area will move
first. Make sure the base is stronger than the damage.
The ram should always be set up to rest on the base.
Tubes are snapped onto the ram to reach the damage.
Figure 9-19 shows a typical setup inside a trunk.
Notice that the base is the wheel house. The wheel
house is curved and, therefore, may not be a stable
base. To overcome this problem, a block of wood is
Goodheart-Willcox Publisher
Figure 9-18. The hydraulic ram on this pulling
equipment provides a constant force to remove
damage.
Goodheart-Willcox Publisher
Figure 9-17. This power post is chained to the floor for
light sheet metal pulls.
Come-along
Power
post
Floor
pots
Hookup to
vehicle
Chain
Ram