All hydraulic motor grader circuitry

• US 4,033,236 A
• Filed: 02/04/1974
• Issued: 07/05/1977
• Est. Priority Date: 12/27/1971
• Status: Expired due to Term

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Americas Company (Caterpillar Incorporated)
• Inventors: Johnson, Howard L., Junck, John A.
• Primary Examiner(s): Geoghegan, Edgar W.
• Application Number:
  US05/652,939
• Time in Patent Office: 1,247 Days
• Field of Search: 91/418, 91/444, 91/462, 91/463, 137/596.18, 60/445
• US Class Current: 91/463
• CPC Class Codes: F15B 13/0417 Load sensing elements; Internal fluid connections therefor; Anti-saturation or pressure-compensation valves
• CPC Class Codes: Y10T 137/87225 Fluid motor

Abstract

A closed center control valve for double acting motors having an inlet passage and a pair of control passages is provided with pre-sized restrictions in the control passages to control the flow rate to the motor so that a pre-selected velocity of movement of the motor is achieved.

Claims

1. The combination of a control valve and a double acting hydraulic motor including a housing having a cylindrical chamber divided by a piston and rod assembly into a head end and a rod end having different fluid volumes, said valve comprising:

a valve body having an inlet passage and a pair of motor control passages one of said motor control passages connected to the head end of said motor and the other of said motor control passages connected to the rod end of said double acting motor;

a cylindrical bore in said housing communicating with said inlet passage and said motor control passage;

a valve spool reciprocably mounted in said bore and movable from a neutral position for controlling the flow of fluid between said inlet passage and said motor control passages; and

,

restricting means in the one of said control passages connected to the rod end of said motor for fixing the size of said one passage in relation to the size of said other passage to the same proportion that the volume of the rod end of said motor bears to the head end of said motor proportioning the flow of fluid to said motor through said control passages for thereby providing the same velocity movement of said motor in either direction.

2. The invention of claim 1 wherein said valve element is a spool having tapered lands defining conical sections extending outward from the center of said spool.

3. The invention of claim 1 comprising means including a spring and sleeve embracing one end of said spool and threaded plug means mounted in one end of said bore and engaging said sleeve for adjustably centering said valve element.

4. The invention of claim 1 comprising an actuating lever pivotally mounted in said housing and operatively connected to operate said valve element;

said pivotal mounting comprising a spherical section carried by said lever and having means defining a fulcrum mounted in said housing and adjustably embracing said spherical section.

5. The invention of claim 1 wherein said restricting means comprises an orifice in each of said control passages.

6. The valve of claim 1 comprising pressure responsive valve means disposed in said inlet passage prior to intersection thereof with said slidable valve element for controlling the flow of inlet fluid to said valve element.

7. The valve of claim 6 wherein said pressure responsive valve means is responsive to pressure in a selected one of said control passages to control said fluid flow.

8. The invention of claim 5 wherein said orifices are removable.

9. The invention of claim 5 wherein said orifices are formed in removable inserts threadably attached in said control passages.