Wiper Arm: Description and Operation
WIPER ARMDESCRIPTION
FRONT
The front wiper arms are the rigid members located between the wiper pivots that protrude from the cowl plenum cover/grille panel near the base of the windshield and the wiper blades on the windshield glass. These wiper arms feature an over-center hinge (6) that allows easy access to the windshield glass for cleaning. The wiper arm has a die cast metal pivot end (4) with a large tapered mounting hole (5) at one end. A molded black plastic cap fits over the wiper arm retaining nut to conceal the nut and this mounting hole following wiper arm installation.
The wide end of a tapered, stamped steel channel (3) hinges on and is secured with a hinge pin to the blade end of the wiper arm pivot end. One end of a long, rigid, stamped steel strap (2), with a small hole near its pivot end, is riveted and crimped within the narrow end of the stamped steel channel. The tip of the wiper blade end of this strap is bent back under itself to form a small hook (1). Concealed within the stamped steel channel is a long tension spring (7) which is engaged with a wire hook to the underside of the die cast pivot end and is hooked through a small hole in the steel strap. The entire wiper arm has a satin black finish applied to all of its visible surfaces.
REAR
The rear wiper arm (1) is the rigid member located between the rear wiper motor output shaft that protrudes from the outer liftgate panel near the base of the liftgate glass opening and the rear wiper blade (2). The wiper arm is constructed of molded black plastic. A hinged pivot end is also molded plastic, except for a tapered metal sleeve (4) that receives the wiper motor output shaft and a plate where the arm retaining nut is supported. A molded plastic cap with a snap feature fits over the wiper arm retaining nut to conceal the nut and the mounting hole following wiper arm installation.
The wiper arm hinge, pivot block and tension spring are all concealed on the underside of the wide end of the arm. A molded plastic wiper arm support (3) is integral to the wiper arm and extends from the lower edge of the arm. The matching wiper blade has two pivot pins that latch into a receptacle concealed within the narrow end of the arm. The rear wiper arm cannot be adjusted or repaired. If damaged or ineffective, the entire wiper arm unit must be replaced.
OPERATION
FRONT
The driver and passenger side wiper arms are not interchangeable. These arms have a letter D (driver) or P (passenger) cast into the lower surface of the pivot end to identify their proper locations. A wiper arm cannot be adjusted or repaired and, if ineffective or damaged, it must be replaced.
The front wiper arms are designed to mechanically transmit the motion from the wiper pivots to the wiper blades. The wiper arm must be properly indexed to the wiper pivot in order to maintain the proper wiper blade travel on the glass. The tapered mounting hole in the wiper arm pivot end interlocks with the serrations on the tapered outer circumference of the wiper pivot shaft, allowing positive engagement and finite adjustment of this connection.
The mounting nuts lock the wiper arms to the threaded studs of the wiper pivot shafts. The spring-loaded wiper arm hinge controls the down-force applied through the tip of the wiper arm to the wiper blade on the glass. The hook formation on the tip of the wiper arm provides a cradle for securing and latching the wiper blade pivot block to the wiper arm.
REAR
The rear wiper arm is designed to mechanically transmit the motion from the rear wiper motor output shaft to the rear wiper blade. The wiper arm must be properly indexed to the motor output shaft in order to maintain the proper wiper blade travel on the glass. The wiper arm support is designed to lift and support the rear wiper arm and blade off of the glass when they are parked. This support and the park ramp on the liftgate outer panel below the glass upon which the support rests also provide an alignment reference to ensure accurate rear wiper arm installation.
The tapered hole in the wiper arm pivot end interlocks with the serrations on the outer circumference of the tapered motor output shaft, allowing positive engagement and finite adjustment of this connection. A hex nut secures the wiper arm pivot end to the threads on the rear wiper motor output shaft and the plastic cap snaps over this connection for a neat appearance. The spring-loaded wiper arm hinge controls the down-force applied through the tip of the wiper arm to the wiper blade on the glass. The receptacle formation on the tip of the wiper arm provides a cradle for securing and latching the wiper blade to the wiper arm.