Trip lock device for a snow plow

Abstract

A trip lock device for replacing a return spring of a snow plow assembly having a trip mechanism. The device includes an extensible body having a first end for connection to a moldboard a second end for connection to a plow frame. A limiting member is provided to the extensible body to limit its range of extension. A method of installing the device involves removing a return spring from a first and second mounting locations and attaching the extensible body to the first and second mounting locations. The device may also include a load-limiting frangible link.

1 . A snow plow assembly comprising a moldboard pivotally connected to a plow frame, at least one return spring biasing said moldboard toward an upright position, 
 a trip lock device having a trip mechanism, the device comprising:    an extensible body comprising a first end connected to the moldboard of the snow plow assembly, and a second end connected to the plow frame of the snow plow assembly; and    a limiting member provided to the extensible body to limit a range of extension of the extensible body.    
   
   
       2 . The trip lock device of  claim 1 , wherein the extensible body comprises a cylinder and a connecting rod.  
   
   
       3 . The trip lock device of  claim 2 , wherein the first end of the extensible body comprises a free end of the connecting rod and the second end of the extensible body comprises an end of the cylinder.  
   
   
       4 . The trip lock device of  claim 1 , wherein the limiting member comprises a piston.  
   
   
       5 . The trip lock device of  claim 1 , further comprising a load-limiting frangible link for connection between a snow plow assembly and one of the first end of the extensible body and the second end of the extensible body.  
   
   
       6 . The trip lock device of  claim 5 , wherein the load-limiting frangible link is one of a sheer pin and a sheer bolt.  
   
   
       7 . The trip lock device of  claim 1 , wherein the extensible body further comprises an adjustment mechanism for adjusting the range of extension.  
   
   
       8 . The trip lock device of  claim 7 , wherein the adjustment mechanism comprises a threaded connecting rod.  
   
   
       9 . A method of installing a trip lock device on a snow plow assembly comprising the steps of: 
 removing a first end of a return spring from a first mounting means provided on a moldboard of the snow plow assembly;    removing a second end of a return spring from a second mounting means provided on a plow frame of the snow plow assembly;    attaching a first end of an extensible body of the trip lock device to the first mounting means; and    attaching a second end of the extensible body to the second mounting means.    
   
   
       10 . The method of  claim 9 , wherein the extensible body comprises a cylinder and a connecting rod.  
   
   
       11 . The method of  claim 10 , wherein the first end of the extensible body comprises a free end of the connecting rod and the second end of the extensible body comprises an end of the cylinder.  
   
   
       12 . The method of  claim 9 , wherein the trip lock device further comprises a limiting member provided to the extensible body to limit a range of extension of the extensible body.  
   
   
       13 . The method of  claim 12 , wherein the limiting member comprises a piston.  
   
   
       14 . The trip lock device of  claim 9 , further comprising a load-limiting frangible link for connection between a snow plow assembly and one of the first end of the extensible body and the second end of the extensible body.  
   
   
       15 . A trip lock device for replacing a return spring of a snow plow assembly having a trip mechanism, the device comprising: 
 an extendable body comprising a connecting rod comprising a first end and a second end,    a cylinder having a longitudinal axis, a first end for connection to a plow frame of the snow plow assembly and a second end for receiving the first end of the connecting rod,    a piston attached to the first end of the connecting rod, the piston being movable along the longitudinal axis within the cylinder to limit a range of extension of the extensible body; and    a load-limiting frangible link for connection between a snow plow assembly and one end of the cylinder.    
   
   
       16 . A trip lock device for replacing a return spring of a snow plow assembly having a trip mechanism, the device comprising: 
 an extensible body comprising a first end for connection to a moldboard of a snow plow assembly, and a second end for connection to a plow frame of the snow plow assembly; and    a limiting member provided to the extensible body to limit a range of extension of the extensible body.    
   
   
       17 . The trip lock device of  claim 16 , wherein the extensible body comprises a cylinder and a connecting rod.  
   
   
       18 . The trip lock device of  claim 17 , wherein the first end of the extensible body comprises a tree end of the connecting rod and the second end of the extensible body comprises an end of the cylinder.  
   
   
       19 . The trip lock device of  claim 16 , wherein the limiting member comprises a piston.  
   
   
       20 . The trip lock device of  claim 16 , further comprising a load-limiting frangible link for connection between a snow plow assembly and one of the first end of the extensible body and the second end of the extensible body.  
   
   
       21 . The trip lock device of  claim 20 , wherein the load-limiting frangible link is one of a sheer pin and a sheer bolt.  
   
   
       22 . The trip lock device of  claim 16 , wherein the extensible body further comprises an adjustment mechanism for adjusting the range of extension.  
   
   
       23 . The trip lock device of  claim 22 , wherein the adjustment mechanism comprises a threaded connecting rod.  
   
   
       24 . A method of installing a trip lock device on a snow plow assembly comprising the steps of: 
 removing a first end of a return spring from a first mounting means provided on a moldboard of the snow plow assembly;    removing a second end of a return spring from a second mounting means provided on a plow frame of the snow plow assembly;    attaching a first end of an extensible body of the trip lock device to the first mounting means; and    attaching a second end of the extensible body to the second mounting means.    
   
   
       25 . The method of  claim 24 , wherein the extensible body comprises a cylinder and a connecting rod.  
   
   
       26 . The method of  claim 25 , wherein the first end of the extensible body comprises a free end of the connecting rod and the second end of the extensible body comprises an end of the cylinder.  
   
   
       27 . The method of  claim 24 , wherein the trip lock device further comprises a limiting member provided to the extensible body to limit a range of extension of the extensible body.  
   
   
       28 . The method of  claim 27 , wherein the limiting member comprises a piston.  
   
   
       29 . The trip lock device of  claim 24 , further comprising a load-limiting frangible link for connection between a snow plow assembly and one of the first end of the extensible body and the second end of the extensible body.  
   
   
       30 . A trip lock device for replacing a return spring of a snow plow assembly having a trip mechanism, the device comprising: 
 a connecting rod comprising a first end and a second end,    a cylinder having a longitudinal axis, a first end for connection to a plow frame of the snow plow assembly and a second end for receiving the first end of the connecting rod,    a piston attached to the first end of the connecting rod, the piston being movable along the longitudinal axis within the cylinder to limit a range of extension of the extensible body; and    a load-limiting frangible link for connection between a snow plow assembly and the end of the cylinder.