The present invention relates to hydraulic lift cylinder assemblies for use in construction equipment, such as skid-steer loaders and similar heavy construction vehicles. More particularly, it relates to an improved adjustable pressure relief valve arrangement which permits variable pressure relief for the cylinder. The adjustable pressure relief arrangement of the present invention allows for relief of pressure in hydraulic lift cylinders when the equipment operator performs a partial stroke of the cylinder or when one end of the lift cylinder is held in a stationary position while the other end of the cylinder is moved downwardly under high load conditions. Hydraulic lift cylinders or jacks are commonly used on heavy equipment, such as skid-steer loaders, to extend a fork lift or loader arm. An example of a skid-steer loader is disclosed in U.S. Pat. No. 4,660,850, assigned to the assignee of the present invention, and hereby incorporated herein by reference. A typical hydraulic cylinder arrangement includes two or more hydraulic cylinders, mounted in line with each other. Hydraulic fluid is provided from the hydraulic system of the skid-steer loader. A pump or other device is used to increase the pressure of the fluid to a desired working pressure for the cylinders. The working pressure is typically controlled by a pressure relief valve, which releases the fluid to tank or a reservoir when a predetermined pressure or pressure range is reached. As hydraulic fluid flows back into the hydraulic system from the cylinder, the pressure of the fluid within the system decreases. When lifting or extending the lift arms of skid-steer loaders, particularly when the lift arms are heavy, it is sometimes necessary to reduce the pressure of the hydraulic system when lowering or extending the lift arm. In addition, it is sometimes desirable to reduce the pressure in the system during partial strokes of the cylinder when performing a variety of tasks. A common method used to reduce the pressure in the hydraulic system is to install a pressure relief valve having a spring-biased valve member into the hydraulic line to be used. The spring bias forces the valve member closed when the system pressure reaches a first setting, and forces the valve member open when the system pressure reaches a second setting, typically a lower setting. Although there are many designs of pressure relief valves for use in hydraulic cylinders, they generally function by reducing the pressure of the hydraulic fluid being used in the cylinder. It would be desirable to provide a pressure relief valve which may be adjusted for use in hydraulic systems to provide relief in a manner which is useful when a skid-steer loader operator performs a partial stroke of the lift cylinders or when one end of the lift cylinder is held stationary while the other end of the cylinder is moved downwardly under high load conditions. The present invention provides such an adjustable pressure relief valve.