Hydraulic actuator for a trip plow

Abstract

A hydraulic actuator that can be used on trip plows to hold the trip blade in its operative downward position and to control the return of the trip blade after tripping. The actuator has a body with first and second ends. A piston rod reciprocates within the tube. A plate with a channel is positioned within the tube a spaced distance from the tube ends. The plate creates an oil reservoir between the plate and the piston rod. A reciprocating piston is positioned within the tube between the second end and the plate. A spring is mounted between the second end and the reciprocating piston and normally biases the reciprocating piston into engagement with the channel normally closing the channel. The piston rod moves in the direction of the plate when the trip blade hits an obstruction, forcing the oil through the channel moving the reciprocating piston and opening the channel allowing oil to flow into an oil chamber created between the reciprocating piston and the plate. The spring biases the reciprocating piston back to the normally closed position and forces the oil into the oil reservoir after the trip blade has cleared the obstruction.

What is claimed is: 
     
         1 . A trip snowplow comprising:
 a plow and body:   a trip blade mounted to said plow body,   a hydraulic actuator connected between said plow body and said trip blade, said hydraulic actuator having a tube with first and second ends, a piston rod extending from said first end, said piston rod having a piston head adapted to reciprocate within said tube;   a plate having a first surface and a second surface, said first surface spaced from said first end and said second surface spaced from said second end, said plate positioned within said tube a space different distance from said first end creating an oil reservoir containing oil between said plate and said piston head;   a channel extending through said first and second surfaces of said plate,   a reciprocating piston position within said tube between said second end and said second surface of said plate;   a spring mounted between said second end and said reciprocating piston said spring normally biasing said reciprocating piston into engagement with said channel normally closing said channel;   said piston rod and said piston head moving in the direction of said plate when said trip blade hits an obstruction, said oil in said oil reservoir being partially forced through said channel against said reciprocating piston moving said reciprocating piston in the direction of said second end and opening said channel allowing said oil to flow into an oil chamber created between said reciprocating piston and the second face of said plate when said reciprocating piston moves in the direction of said second end, said spring biasing said reciprocating piston back to said normally closed position and forcing said oil from the oil chamber into said oil reservoir after said trip blade has cleared said obstruction whereby said trip blade trips upon hitting an obstruction and is returned under controlled force to its normal position period.   
     
     
         2 . The trip snowplow of  claim 1 , further including an oil passage extending through said reciprocating piston and a check valve located in said oil passage; said check valve allowing oil to flow through said passage from said second side to said first side. 
     
     
         3 . The trip snowplow of  claim 1 , further including a second check valve located in said channel; said second check valve allowing oil to flow through said channel from said first side to said second side. 
     
     
         4 . The trip snowplow of  claim 1 , further including a nose extending from said reciprocating piston in the direction of said channel, said nose normally closing said channel. 
     
     
         5 . The trip snowplow of  claim 4 , wherein said nose has a truncated cone shaped free end. 
     
     
         6 . The trip snowplow of  claim 1 , wherein said channel has a first opening adjacent said first surface and a second opening adjacent said second surface. 
     
     
         7 . The trip snowplow of  claim 6 , wherein said channel second opening is recessed. 
     
     
         8 . The trip snowplow of  claim 7 , further including a nose extending from said reciprocating piston in the direction of said second opening, said nose normally closing said channel, said nose having a truncated cone shaped free end that is received within said second opening to normally seal said channel. 
     
     
         9 . A hydraulic actuator comprising:
 a tube with first and second ends, a piston rod extending from said first end, said piston rod having a piston head adapted to reciprocate within said tube;   a plate having a first surface and a second surface, said first surface spaced from said first end and said second surface spaced from said second end, said plate positioned within said tube a space different distance from said first end creating an oil reservoir containing oil between said plate and said piston head;   a channel extending through said first and second surfaces of said plate,   a reciprocating piston position within said tube between said second end and said second surface of said plate;   a spring mounted between said second end and said reciprocating piston said spring normally biasing said reciprocating piston into engagement with said channel normally closing said channel;   said piston rod and said piston head moving in the direction of said plate when said trip blade hits an obstruction, said oil in said oil reservoir being partially forced through said channel against said reciprocating piston moving said reciprocating piston in the direction of said second end and opening said channel allowing said oil to flow into an oil chamber created between said reciprocating piston and the second face of said plate when said reciprocating piston moves in the direction of said second end, said spring biasing said reciprocating piston back to said normally closed position and forcing said oil from the oil chamber into said oil reservoir after said trip blade has cleared said obstruction whereby said trip blade trips upon hitting an obstruction and is returned under controlled force to its normal position period.   
     
     
         10 . The trip snowplow of  claim 9 , further including an oil passage extending through said reciprocating piston and a check valve located in said oil passage; said check valve allowing oil to flow through said passage from said second side to said first side. 
     
     
         11 . The trip snowplow of  claim 9 , further including a second check valve located in said channel; said second check valve allowing oil to flow through said channel from said first side to said second side. 
     
     
         12 . The trip snowplow of  claim 9 , further including a nose extending from said reciprocating piston in the direction of said channel, said nose normally closing said channel. 
     
     
         13 . The trip snowplow of  claim 12 , wherein said nose has a truncated cone shaped free end. 
     
     
         14 . The trip snowplow of  claim 9 , wherein said channel has a first opening adjacent said first surface and a second opening adjacent said second surface. 
     
     
         15 . The trip snowplow of  claim 14 , wherein said channel second opening is recessed. 
     
     
         16 . The trip snowplow of  claim 15 , further including a nose extending from said reciprocating piston in the direction of said second opening, said nose normally closing said channel, said nose having a truncated cone shaped free end that is received within said second opening to normally seal said channel.