Mechanical arm 布匹机、切条机 JKX rotary vane vacuum pump oil lubrication efficiency JKH piston type high-efficiency energy-saving environment-friendly vacuum pump MH-2 high vacuum energy-saving series ZQL type axial pneumatic clutch series JZJWLW series Roots vertical unoiled WLK series vertical vacuum pump oil W, WY type of reciprocating vacuum pump 2X rotary vane vacuum pump ZJ series Roots vacuum pump 2SK, 2SK-P1 two-stage water ring vacuum pump JZJS roots water ring vacuum unit JZJX series Roots Cixuan vane vacuum pump unit VPS dry screw vacuum pump Stainless steel water ring vacuum pump 2BV vacuum pump series