Load balancer with balance override control

Claim 2

In a load balancer, a frame, a load support arm movably mounted on said frame, a power cylinder having a piston movably connected to said arm to act against a load connected to said arm, means connectable to a source of fluid under pressure for applying fluid to said cylinder, a control circuit interposed between said means and said cylinder, said control circuit including a pilot operated valve for directing fluid to and from said cylinder, said valve being responsive to a control fluid pressure and cylinder fluid pressure whereby an imbalance in said fluid pressures resulting from movement of said piston caused by manual movement of the load causes said valve to restore a balance in said pressures, and balance override means for selectively directing a fluid pressure greater than said control fluid pressure to said pilot operated valve to cause said valve to direct a greater fluid pressure to said cylinder to move the load and without changing the established control fluid pressure whereby the load may again be balanced by said established control pressure.

Claim 3

In a load balancer, a frame, a load support arm movably mounted on said frame, a power cylinder having a piston movably connected to said arm to act against a load connected to said arm, means connectable to a source of fluid under pressure for applying fluid to said cylinder, a control circuit interposed between said means and said cylinder, said control circuit including a pilot operated control valve for directing fluid to and from said cylinder, said control valve being responsive to a control fluid pressure and cylinder fluid pressure whereby an imbalance in said fluid pressures causes said valve to restore a balance in said pressures, means for establishing plural control pressures of different values corresponding to different load weights, and balance override control means including a bias regulator valve which senses the control fluid pressure for establishing a fluid pressure a fixed amount higher than any one of said control fluid pressures, and valve means for blocking said control fluid pressure from the control valve and applying said higher fluid pressure to the control valve to direct a greater fluid pressure to said cylinder and cause lifting of the load.

Claim 4

In a load balancer, a frame, a load support arm movably mounted on said frame, a power cylinder having a piston movably connected to said arm to act against a load connected to said arm, means connectable to a source of fluid under pressure for applying fluid to said cylinder, a control circuit interposed between said means and said cylinder, said control circuit including a pilot operated control valve for directing fluid to and from said cylinder, said control valve being responsive to a control fluid pressure and cylinder fluid pressure whereby an imbalance in said fluid pressures causes said valve to restore a balance in said pressures, means for establishing plural control pressures of different values corresponding to different load weights, and balance override control means including a bias regulator valve which senses the control fluid pressure for establishing a fluid pressure a fixed amount higher than any one of said control fluid pressures, and valve means for blocking said control fluid pressure from the control valve and applying said higher fluid pressure to the control valve to direct a greater fluid pressure to said cylinder and cause lifting of the load.

Claim 5

A load balancer as defined in claim 2 wherein the balance override means further includes means for reducing the control fluid pressure applied to the control valve to cause a reduction in cylinder pressure and lowering of the load.

Claim 6

A load balancer as defined in claim 3 wherein said control valve has a position to connect the cylinder to exhaust and is moved to said position when the balance override means reduces the control fluid pressure applied to the control valve, and means in said exhaust line to control the rate of fluid flow to exhaust and therefore the rate of descent of said load.

Claim 7

In a load balancer, a frame, a load support arm movably mounted on said frame, a power cylinder having a piston movably connected to said arm to act against a load connected to said arm, means connectable to a source of fluid under pressure for applying fluid to said cylinder, a control circuit interposed between said means and said cylinder and having an adjustable air pressure regulating valve to set a control fluid pressure at a value to obtain a balance of the load, said control circuit including a pilot operated control valve for directing fluid to and from said cylinder, said control valve being responsive to said control fluid pressure and cylinder fluid pressure whereby an imbalance in said fluid pressures causes said valve to restore a balance in said pressures, and balance override control means including a bias regulator valve acted upon by said control fluid pressure for establishing a fluid pressure a fixed amount higher than said control fluid pressure, and valve means for blocking said control fluid pressure from the control valve and applying said higher fluid pressure to the control valve to direct a greater fluid pressure to said cylinder and cause lifting of the load.

Claim 8

In a load balancer, a frame, a load support arm movably mounted on said frame, a power cylinder having a piston movably connected to said arm to act against a load connected to said arm, means connectable to a source of fluid under pressure for applying fluid to said cylinder, a control circuit interposed between said means and said cylinder and having an adjustable air pressure regulating valve to set a control fluid pressure at a value to obtain a balance of the load, said control circuit including a pilot operated control valve for directing fluid to and from said cylinder, said control valve being responsive to said control fluid pressure and cylinder fluid pressure whereby an imbalance in said fluid pressures causes said valve to restore a balance in said pressures, and balance override control means including a bias regulator valve acted upon by said control fluid pressure for establishing a fluid pressure a fixed amount higher than said control fluid pressure, and valve means for blocking said control fluid pressure from the control valve and applying said higher fluid pressure to the control valve to direct a greater fluid pressure to said cylinder and cause lifting of the load.