Lift axle control system

In a control system for a lift axle in a two-axle suspension for wheeled vehicles wherein:

• first and second axles are connected to a vehicle frame through first and second suspensions, respectively;
• said second suspension having means to mount said second axle for movement between a raised position and a lowered position, and actuation means for moving said second axle between said raised and lowered positions;
• said second axle having wheels for supporting engagement with the ground when the second axle is in the lowered position and said wheels being out of contact with the ground when said second axle is in a raised position;
• control means having a means to detect a load on the first axle and for automatically raising said second axle to said raised position when the load on the first axle is below a first predetermined value, and a means for automatically lowering said second axle to said lower position when the load on said first axle is above a second predetermined value which is greater than the first predetermined value, and means to delay the operation of said actuation means to lower said second axle upon detection of a load on said first axle to compensate for road bumps;
• the improvement which comprises:
• means to manually override said control means, but only for a relatively short period of time, when said second axle is in a lowered position so that said second axle can be selectively raised for short periods of time to enhance maneuverability of said vehicle during said relatively short periods of time.

In a control system for adjusting loads on a two-axle suspension for wheeled vehicles wherein:

• first and second axles are connected in tandem to a vehicle frame through first and second suspensions, respectively;
• said second suspension having means to increase and decrease the load on said second axle;
• and
• control means having a means to detect a load on the first axle and for automatically controlling the load on said second axle to decrease the load thereon when the load on the first axle is below a first predetermined value, means for automatically increasing the load on said second axle when the load on said first axle is above a second predetermined value which is greater than the first predetermined value and means to delay the automatic control of the load on the second axle when the load on the first axle is above the second predetermined value to compensate for road bumps;
• the improvement which comprises:
• said load-detecting means comprising electrical sensing means and said control means comprising electrical circuit means to control the load on said second axle responsive to a signal from said second electrical circuit means.

In a control system for adjusting loads on a two-axle suspension for wheeled vehicles wherein:

• first and second axles are connected in tandem to a vehicle frame through first and second suspensions, respectively;
• said second suspension having means to increase and decrease the load on said second axle;
• and
• control means having a means to detect a load on the first axle and for automatically controlling the load on first second axle to decrease the load thereon when the load on the first axle is below a first predetermined value, and a means for automatically increasing the load on said second axle when the load on said first axle is above a second predetermined value which is greater than the first predetermined value;
• the improvement which comprises:
• means to manually override said control means, but only for a relatively short period of time, when the load on said first axle is above said second predetermined value so that the load on said second axle can be selectively decreased for short periods of time to enhance maneuverability of said vehicle during said relatively short periods of time.