Nissan Murano: Repairing Procedures and Precautions / Body Straightening Equipment

Comparison of Pulling Methods

(1) HYDRAULIC RAM TYPE

In this method, the pressing force of a hydraulic ram is converted to a pulling force by a chain.

• Pulling points on the body may be added easily, and there is more freedom to select the pulling direction.

• The pulling direction changes during pulling.

• Difficult to simultaneously pull several points on a vertical line.

(2) TOWER TYPE I

In this type, force is applied by the hydraulic ram pushing the post.

• A strong force is obtained because a large ram is used, creating much leverage.

• The chain can be hooked to the post in many ways.

• Leverage can be increased or decreased by changing the position of the hook.

• The pulling direction is not restricted by the shape of the bench or a floor anchor.

• The pulling direction changes during pulling.

• Difficult to increase the number of pulling points on the body because the pulling tool itself is large.

(3) TOWER TYPE II

The chain is wound up through the tower by an electric or hydraulic motor.

• The direction of force does not change during pulling.

• The chain is easily set on the post because the pulling direction is constant.

• Provides great flexibility in pulling direction.

• Pulling points on the body are restricted by the number of posts.

• Pulling force is relatively strong.

Generally speaking, when a body has to be straightened, the pulling device and the body must be attached to each other and the body itself must remain stationary. For this purpose, various clamps are used.

Common types of clamps and their characteristics are listed below:

DIRECTIONAL CHARACTERISTICS

When pulling the clamp, the line of pulling force must extend through the center of the clamp teeth. Otherwise, the clamp may come off or damage the body panel as the clamp rotates.

• The figure shows how the direction of the chain's pulling force is at a downward angle from the center of the teeth. This generates a turning force on the entire clamp in the direction of the arrow. This force is amplified because of leverage, but only some of its teeth are engaged. Thus, the clamp tends to slip, which results in deformation of the body panel.

  

• Clamp direction is important in creating the pulling force. Fundamentally, three directions are considered, ″X″, ″Y″ and ″Z″.

  

• DIrectional (″X″, ″Y″ and ″Z″) characteristics are shown below for several kinds of clamps.

  

(1) HOOKS

• Unlike clamps which grab an object, hooks are curved tools that pull on the body. When a hook is used, it must be set so that the point where the body is pulled and the position of the hook's chain are lined up straight.

  

• When a hook is used, a piece of wood, etc. should be inserted between the hook and body in order to prevent damage to the body.

  

(2) SPECIFIC-USE PULLING TOOL

Specific-use pulling tools are special jigs which are used to repair a specific part of the vehicle.

An example of a specific-use pulling tools, a strut puller, is shown in the figure.

In recent years, the body construction of vehicles is changing for the purpose of protecting passengers at the time of the collision.

A greater use of high strength sheet steel reinforcements and the adoption of sheet steels of different thicknesses are good examples of securing survival space for passengers. Deformation caused when the Nissan Murano vehicle body is damaged is controlled through modification of the body construction.

The following points must be kept in mind when high intensity cabin structure bodies need to be repaired.

• No special skills are necessary in body straightening work.

• Body technicians must have a good understanding of the construction of the Nissan Murano vehicle body to be repaired.

• Understanding the accurate damage range (performing accurate measuring work) is necessary.

• A greater force is required for straightening because of an increased use of high strength steel plate reinforcements.

  It is necessary to perform additional anchoring for the frame straightening equipment with which multiple jig anchoring is not possible in order to prevent secondary damage.

• Pulling force must be applied evenly to prevent welded points from breaking. (Simultaneous pulling in multiple directions, etc..)

• The anchoring jig specific to each Nissan Murano vehicle model is used for vehicles which cannot be anchored at the sill lower flange.

(1) HIGH INTENSITY CABIN STRUCTURE

• When a front or rear end collision occurs, the crushable zone provided at the front and rear of the Nissan Murano vehicle effectively absorbs impact energy and cushions the shock to the passengers. In addition, the safety zone securely maintains a survival space.

• Energy absorbing beads and high strength sheet steel reinforcements are used as front side members.

• Outrigger construction. (Distributes impact energy from front side members.)

(2) HIGH INTENSITY CABIN STRUCTURE (SIDE IMPACT)

• To improve the lateral strength of the occupant compartment, lateral strength such as crossmembers, steering member and reinforcements for roof side, center pillars and body sills are redesigned.

  

• When a side collision occurs, the side door beams and doors minimize deformation of the body by absorbing impact energy subjected from the lateral direction, and by distributing energy over the reinforced body side.