| A plunger with a helical moves in a barrel with a suction and spill port. The plunger turns in the barrel aligning the helical grove with the spill port for varying end of injection. Cavitation is reduced by a spring loaded piston and orifice which can absorb and damp out fluctuation. Adjustment can be done by adjusting either height of plunger or barrel. In VIT adjustment is done by adjusting barrel, the barrel has an outside thresh portion which engages into the timing guide operated by a toothed rack. Movement of the rack causes the pump barrel to move vertically up or down relative to the pump plunger. |
Since very small needle lift is obtained in the test equipment result in an unequal pressure distribution in the cut off shaft resulting in a hard contact in a small area along with high frequency oscillations, low lubricity of test oil will increase the chance of seizure. Full lift and high lubricity of heavy oil eliminates this risk of seizure during normal operation.( Always open and clean slide type valves before testing as cold sticky heavy oil along with small clearances can cause restriction in the movement of the spindle).
Comments