BUMPER AS 1274576 - Caterpillar

When cylinder (5) closes the jaw under high resistance, the speed control valve will shift into a maximum power operation known as "Boost Mode". This mode will activate the two intensifier valves.When the operator closes the jaw, auxiliary control valve (18) shifts to the right. When auxiliary control valve (18) is shifted to the right, flow is directed from the host machine through the speed control valve to the head end of cylinder (5). The pressure on the head end of cylinder (5) causes the cylinder rod to extend, which closes the jaws.Simultaneously, oil flows to relief valve (14), pilot valve (15), regeneration valve (6), intensifier (4) and intensifier (7). Spring force keeps relief valve (14) closed when oil pressure is below the relief setting.The increased resistance from crushing material with the jaws of the work tool, causes an increase in oil pressure that is sensed in the speed control valve.This pressure increases and eventually overcomes the setting of relief valve (14). The setting of relief valve (14) is 28000 kPa (4060 psi). This condition opens relief valve (14) allowing oil to flow to the left side of pilot valve (15). This action causes pilot valve (15) to shift to the right against spring (17). Oil is directed from pilot valve (15) to the right end of regeneration valve (6).When regeneration valve (6) moves to the left, oil is directed from the rod end of cylinder (5) back to the hydraulic tank. The direction of the oil flow to the tank causes the speed of the jaws to decrease. When regeneration valve (6) moves to the left, oil is also sent to sequence valves (1).When maximum host machine pressure is lower then cylinder pressure, check valve (12) closes. This condition is the start of the "Boost mode". When maximum host pressure stays above cylinder pressure, boost mode will not be activated (resistance crushing material too low to increase oil pressure).Note: When sequence valves (1) are supplied with oil, intensifier valves (4) and (7) are activated. An active intensifier is recognizable by a soft ticking sound in the background during jaw closing operation.Intensifier Valve Operation
When activated, the piston and valve group within the intensifier valve will shuttle back and forth. This action will provide higher pressure oil to the cylinder which is required to overcome the higher resistance of crushing material.Upward Movement
Note: The following describes the operation of left intensifier valve (4). The operation will be the same for right intensifier valve (7).
Illustration 5 g03429191
Cross section and schematic views of intensifier valve (upward movement)
(A) Cavity
(B) Cavity
(C) Passage
(D) Passage
(V) Passage
(W) Passage
(HD) Port (outlet)
(UB1) Port (inlet)
(UB2) Port (inlet)
(2) Check valve
(3) Check valve
(8) Intensifier piston group
(9) Check valve
(10) Check valve
(19) Passage
(20) Check valve
(21) Check valveSupply oil is sent to intensifier valve (4) through sequence valve (1). When sequence valves (1) are shifted downward, oil travels through passage (C). Simultaneously, supply oil will flow to cavity (A) through check valve (10) and check valve (21).As intensifier piston group (8) is forced upward by oil