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A standardized design forms the basis of our custom built hydraulic rams. The internal parts are of a well-proven design featuring robust sealing and quality materials. The desired cylinder bore size and piston rod diameter, are calculated from information supplied by the customer. The ram is then designed to meet the customers requirements of stroke length, closed center length, and mounting style. We retain stocks of piston rod and cylinder tube materials, also standard ram mounts and the internal components. This allows us to produce custom-built rams quickly. Bore sizes from 40mm to 250mm are available from our standard range. Larger sizes are available as custom designed rams. Our hydraulic rams are available as the following
generic types.
DOUBLE ACTING
Double acting rams can exert force in two directions. Under the influence of hydraulic pressure the piston rod of a double acting ram will both extend and retract. The diagram shows a typical double acting ram. Pumping fluid under pressure into port A (full bore ) will extend the piston rod, the force exerted will be dependant on the cylinder bore diameter and the fluid pressure. Pumping fluid into port B ( annulus ) will cause the piston rod to retract, the force exerted is dependant on the cylinder bore diameter, the piston rod dia, and the fluid pressure. DOUBLE ACTING RAM
SINGLE ACTING
Single acting rams can exert force in only one direction. Under the influence of hydraulic pressure the piston rod of a single acting ram will either extend or retract. The diagram shows a typical ‘out stroking’ single acting ram, pumping fluid under pressure into port A (full bore ) will extend the piston rod, the force exerted will be dependant on the cylinder bore diameter and the fluid pressure. The piston rod can only be retracted by the influence of some external force (usually the weight of the load or the machine it’s self ). ‘In stroking’ single acting rams are similar to the double acting ram with the exception that fluid is supplied to the annulus port only. The force exerted is dependent on the cylinder bore diameter, the piston rod diameter and the fluid pressure. Single acting rams generally only have one service port. The non pressure side of the cylinder must be vented to allow air to pass in and out as the piston moves. In arduous conditions single acting rams can tend to suffer from rusting or pitting of the bore as moist air passes in and out of the non pressure side of the cylinder. SINGLE ACTING RAM
DISPLACEMENT
A displacement ram is a special form of single acting ram, and can be of the ‘out stroking’ style only. The diagram shows a displacement ram. Pumping fluid into port A will fill the space around the piston rod, as there is a seal between the gland and the rod the oil is contained, pumping further fluid into the cylinder will displace the volume of the piston rod and it will stroke out. DISPLACEMENT RAM The force exerted is dependent on the piston rod diameter and the fluid pressure. Since there is no moist air passing in and out of the cylinder problems associated with rusting bores are avoided. A disadvantage is that a displacement ram of the same capacity of an ‘out stroking’ single acting ram, will be larger in diameter.
MULTISTAGE TELESCOPIC
Multistage telescopic rams are most commonly single acting and "out stroking", although we do produce double acting telescopics and special rams which are a combination of the three generic types. A telescopic cylinder is used to obtain a longer stroke length from a given closed length. DOUBLE ACTING TELESCOPIC RAM SPECIALSOur design capability allows us to produce special rams to suit an exact special requirement of load stroke length or mounting style. The following example was produced for a high pressure heavy duty application on a metal shearing machine. HEAVY DUTY HIGH PRESSURE SHEAR RAM |
