Hendrickson ULTIMAAX 54K, Technical Procedure

Alignment & Adjustments 

28

 17730-299

ULTIMAAX

®

 for Fire and Rescue Vehicles

Proper alignment is essential for maximum ride quality, performance, and tire service life . The fol-

lowing recommended alignment procedure as described below, should be performed if excessive 

or irregular tire wear is observed .

NOTE  

Proper vehicle alignment can only be achieved when all axles are aligned to the vehicle’s 

centerline and the steering axle’s caster, camber and toe-in settings are within specifications . 

FIGURE 7-2

INSPECTION

1 .  Use a work bay with a level, flat surface .
2 .  Relax the suspension by slowly moving the vehicle back and forth several 

times in a straight line . This will slacken or loosen the suspension as the 

vehicle is positioned . End with all wheels positioned straight ahead .

3 . 

DO NOT 

set the parking brake . Chock the front wheels of the vehicle .

4 .  Verify the vehicle system air is at full operating pressure .
5 .  Verify all suspension components are in good condition . Repair or replace 

any worn or damaged suspension components before proceeding with the 
alignment process .

6 .  Ensure all drive axle tires are at the same size .
7 .  Securely clamp a six-foot piece of 

STRAIGHT

 bar stock or angle iron across 

the lower frame flange as shown in Figure 7-2 . Select a location for the bar 

stock or angle iron as far forward of the drive axle as possible where compo-

nents will not interfere .

8 .  Accurately square the bar stock or angle iron to the frame using a carpen-

ter’s square .

9 .  Using a measuring tape, measure from the straight edge to the forward face of the front drive 

axle arms on both sides of the vehicle as shown in Figure 7-2, dimensions 

A

and 

B

 .

10 . Calculate the difference between measurements 

A

and 

B

 .

a .  If the 

front

 drive axle is within vehicle manufacturer’s specifications, proceed to check the 

rear drive axle (Step 11) .

b .  If alignment of the 

front

 drive axle 

IS NOT 

within the vehicle manufacturer’s specifications, 

then the alignment of this axle 

MUST 

be corrected 

BEFORE 

measuring the rear drive axle 

alignment (Step 11) . 

c .  If the suspension is equipped with bar pin end bushings, correct the alignment of this axle 

by following the bar pin alignment instructions in this section .

NOTE  

Since the remaining drive axle will be aligned relative to the front drive axle, it is essential that the 

front drive axle is aligned within the vehicle manufacturer’s specifications prior to the alignment 

of the remaining drive axle .

11 . Using a trammel bar, measure the distance from the spindle center of the 

front

 drive axle to the 

spindle center of the rear drive axle on both sides of the vehicle; see Figure 7-2, 

C

and 

D

 .

12 . Calculate the difference between measurements 

C

 and 

D

 .

a .  If the measurements are within the vehicle manufacturer’s specifications, then the 

rear

drive axle alignment is acceptable .

b .  If alignment of the 

rear

 drive axle 

IS NOT

 within the vehicle manufacturer’s specifications, 

then the alignment of this axle 

MUST

 be corrected . 

c .  If the suspension is equipped with bar pin end bushings, correct the alignment of this axle 

by following the Bar Pin with Shims Alignment instructions in this section .

13 . Recheck measurements to confirm adjustments . Repeat Steps 10 through 12 until the correct 

alignment is achieved .

14 . After all drive axles are aligned, check the pinion angle of each drive, refer to the Axle Pinon 

Angle in this section .

D

Trammel

Bar

A

B

C

FRONT

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