Operation - Section 3 10/00 OM3023 Page 3-30 Operating Instructions OPERATOR SEAT The operator's seat is a fully adjustable air ride seat with 5 mechanisms to adjust the height, firmness, backrest angle, front-to-rear position, and lumbar support for the operator. All adjustments must be made while sitting in the seat with the keyswitch "ON". 4. The Front-To-Rear position of the seat is adjusted by pulling up on the bar located at the base of the seat in the center ([E], Figure 3-5), then sliding the seat horizontally.
Adjust the fore / aft position of the seat so that the throttle and brake pedals are comfortably accessible by pulling up on the bar located at the base of the seat in the center, then sliding the seat horizontally. The steering column angle may also be adjusted at this same time to fur- ther enhance the operator ease and comfort. Operator's Seat Functions & Adjustments: 1. Height Adjustment - is made by using the height adjustment lever, located on the left front corner of the seat just below the seat cushion (Figure 3-5). Pushing DOWN [A] on the lever causes the front of the seat to tilt up or down. Pulling UP [B] on the lever causes the rear of the seat to tilt up or down.
By alternately tilting the front, and then the rear, of the seat, the height of the seat is changed. 5. The Lumbar Support has 5 positions that are mechanically selected by rotating the round knob ([F], Figure 3-5) located on the left side of the backrest. It can be adjusted so that there is no lumbar support. Adjust the lumbar support by rotating the knob to the desired position. There are 8 separate positions possible. To find the best seat position, first adjust the height of the seat to its LOWEST position. By alternately tilting the front down, then the rear down, the seat will move to its lowest position. NOTE:
It is best to start with the seat mechani- cally adjusted to its lowest point, since increas- ing air pressure for a firm ride (see Weight Adjustment below) will raise the seat slightly. After the firmness is adjusted to a comfortable level (by increasing air pressure), the height of the seat can be evaluated and adjusted higher, if necessary, using the height adjustment lever. 2. Weight Adjustment - Firmness of the ride is adjusted by using the weight adjustment knob on the front center of the seat, just below the cushion ([D], Figure 3-5).
PUSH IN the weight adjustment knob to increase the air pressure in the seat, increasing the stiffness of the seat for a firmer ride (less vertical movement). For a softer ride (more vertical movement), PULL OUT the weight adjustment knob to reduce air pressure and decrease the stiffness of the seat. Adjust the firmness by pushing in the weight adjustment knob. The amount of air pressure may need to be increased or decreased slightly after the truck is operating to adapt to varying haul road conditions. The seat will raise slightly when adding air. 3.
Backrest Angle - is adjusted by pulling up on the lever ([C], Figure 3-5) located on the right front corner of the seat just below the cushion, and leaning forward or backward. FIGURE 3-5. OPERATOR SEAT NOTE: Some seats may not have the self-contained air compressor; these seats may require the truck engine to be operating, or at least, have the air system fully charged to make correct seat adjustments. Adjust the backrest angle by pulling up on the lever located on the right front corner of the seat just below the cushion, and leaning forward or backward.