290,688. Miller, H. C., and Sumner, G. P. Nov. 22, 1926. Safety-valves. - To prevent injury due to generation of excessive pressure in a fluid pressure jack, an adjustable spring- pressed safety valve is mounted in the base of the jack so as to normally close a port connecting the ram cylinder and the reservoir. The base 1 of the jack is formed with a recess 10 which communicates by ports 6, 9 with the ram cylinder 7 and reservoir 11, respectively. The port 6 is normally closed by a spring-pressed safety valve 2 provided with an aligning collar 5, the spring abutting against an adjustable screwed plug 4. A ball valve may be used instead of a conical valve. When the pressure in the ram cylinder becomes excessive, the valve opens and pressure fluid escapes into the reservoir. In a modification the valve is vertically mounted in a sleeve screwed into the base. The valve 16, Fig. 3, may be mounted on a leaf spring 15 which is adjustably clamped to the base by a screwed stud 18 and clamping plates 17. The leaf spring 15, Fig. 4, may be curved and the ball valve 20 secured in a recess in a valve support 16<a>. The leaf spring 15, Fig. 5, may be secured to a bracket 22 mounted on a pivot 23 and fitted with a screwed stud 24 for adjusting the spring tension.