A dump is lowrider slang for a normally closed solenoid valve that controls the downward movement of the car. The valve is opened when the car is dumped on the switch and the weight of the car on the open valve lets the car down. The oil returns back to the reservoir tank on the pump when the car is dumped. In the lowrider world there are two main types of dumps, needle ( poppet ) dumps and spool dumps. Needle dumps include Delta dumps and other similar dump valves. The family of needle ( poppet ) dumps are originally intended for industrial use. These valves are made by Delta, Sterling, HydroForce and Legend. ( Italian ) Pressure lock can be a problem in some of the valves like the Waterman valves are not a good choice for heavy use or on a heavy car. Needle dumps are good for street use but are limited and can have problems in heavy competition use. On the Delta cartridges you may have noticed that the electric solenoid may become stuck on the cartridge. This is because they are not meant for heavy use and that the cartridge has expanded from the extreme pressure of hopping. Now most kits come with the Italian dumps now because of the problem with Delta cartridges. On some dumps we have tested we have found that steel dumps are the best for electric conductivity and are stronger than aluminum body dumps that may distort over time.
The spool type dump valve group includes Adel P/N 23500-2, Regular Adex P/N 23500-22, Super Duty Adex P/N 23500-23 and Hydro Aire valves. ( Don’t hop on a Hydro Aire #6 or #8 dump! ) Many other valves are part of this group. All of these valves are sometimes called candlestick dumps because of the solenoids. They use Amphenol 97 Series formerly ( MIL-C-5015 ) 14s ( shell ), 9s ( insert ) P/N 3106A straight plug connectors on the solenoids. The original Adel dump comes from military aircraft from the 50’s. On the aircraft they are called just solenoid valves and brake valves. This family of dumps is the best for hopping because they have almost no loss of pressure and close pretty much instantly. Adex is a high quality reproduction of the original Adel dump valve and many hydraulic companies sell Adex brand valves. Remember that the Adel valve was in used in military aircraft so the quality is superb because it had to meet military requirements. The original Adel valves are a rare find, since they are no longer made. Adel was bought out by Hydro Aire in 1972. The Adex is a high quality valve that you can still get your hands on. Adex takes care in manufacturing their products and offers a warranty on their valves. Watch out for cheap imitation dumps that look like Adel and Adex valves, they are not worth the trouble from the stories we have heard. Sometimes the generic valves will have a P/N 1996-H on them.
For more on Aircraft Valves visit our section on Square Dumps.
All dumps occasionally need some minor maintenance by changing the O-ring when they are worn. Delta style valves are the easiest to maintain since there is really only three major parts when it is disassembled. The cartridge on a delta style dump should never be over tightened and the nut that holds on the solenoid onto the cartridge should only be finger tight.