Leveling Unit Functional Check
A Boge Hydromat leveling unit is located in the center of the rear axle. When the vehicle is unladen the leveling unit has little effect. The unit is self- energizing and hence the vehicle has to be driven before the unit becomes effective, the time taken for this to happen being dependent upon the vehicle load, the speed at which it is driven and the roughness of the terrain being crossed. If the vehicle is overloaded the unit will fail to level fully and more frequent bump stop contact will be noticed. Should the vehicle be left for a lengthy period, e.g. overnight, in a laden condition, it may settle. This is due to normal internal fluid movement in the unit and is not detrimental to the unit performance.
Before carrying out the checks below, verify that the vehicle is being operated within the specified maximum loading capabilities. If the leveling unit is then believed to be at fault, the procedure below should be followed.
- Check the leveling unit for excessive oil leakage, and if present the unit must be changed. Slight oil seepage is permissible.
- Remove excessive mud deposits from underneath the vehicle and any heavy items from inside the vehicle that are not part of the original equipment.
- Measure the clearance between the rear axle bump pad and the bump stop rubber at the front outer corner on both sides of the vehicle. SeeFig 1 . The average clearance should be in excess of 67 mm (2.8 in). If it is less than this measurement remove the rear springs and check their free length against the "Road Spring Data". See Fig 2 . Replace any spring whose free length is more than 20 mm (0.787 in) shorter than the figure given. If after replacing a spring the average bump clearance is still less than 67 mm (2.8 in), replace the leveling unit.
- Replace any spring whose free length is more than 20 mm (0.787 in) shorter than the measurement given. If after replacing a spring the average bump clearance is still less than 67 mm (2.8 in), replace the leveling unit.
- With the rear seat upright, load 450 kg (992 Lbs.) into the rear of the vehicle, distributing the load evenly over the floor area. Check the bump stop clearance, with the driving seat occupied.
- Drive the vehicle for approximately 5 km (3 miles) over undulating roads or graded tracks. Bring the vehicle to rest by light brake application so as not to disturb the vehicle loading. With the driving seat occupied, check the bump stop clearance again.
- If the change in clearance is less than 20 mm (0.787 in) the leveling unit must be replaced.