Truck Wash


July 31, 2010                                                                                                                                                                                                                                                                              ISSUE 224




Tru Shine Truck Wash operates a truck wash for trucks that are used to haul pigs and some cattle to a next door slaughterhouse.  There are a lot of wood shavings, some manure, and a nasty amount of sand, rocks and pebbles in the flow.  They pump from a collection pit, with a 4" Houle, to a paired set of Vincent VDS-42M sidehill screens.  From there the solids go into a  Model KP-16 screw press.


What a surprising application!  This truck wash has 30 to 35 employees.  They haul away two to three big dump truck loads a day of press cake.  They run 24-hours a day.  It is a locally owned business, and there is no trade journal or association.  How do we find the rest of them?


They use 2.5 million gallons of water per month.  The press must run at something around 150 to 250 gpm when the pump is on.


They replaced the screw after about a year.  Seven months later it was already badly worn down again.  This time we sent a screw with lots of Ultinium.  Fortunately for Tru Shine, it is a rental press.


Each morning they open the cone and spray lubricant on the screw shaft.  They do this because they noticed that otherwise wood chips get into the cone bushing and the amps go up.


This press uses the rotating cone feature.  When the press was new, they had to replace the cone drive pins a few times.  The current design, with big diameter pins, has been working just fine.


They have large diameter wheels with bronze bushings.  These have worked well.  They replaced the wheel bushings just once.  They run around 50 psi air pressure on the discharge cone.


The Racing Ring wore down once so they turned it around to wear down the other side.


They had wanted to interlock the press so that it would not run unless the pit pump was running.  (The impeller in the pit pump has lasted two years.)  But the pump runs on and off most of the time, so the press is left in continuous operation.


When the pump turns on it floods the sidehills.  The inlet hopper of the press fills up, and then the collection pan of the sidehills fills.  They have a timer set to shut off the pump at that point.  The press rapidly draws down the level.  Then the press keeps running empty until the pump kicks on again in a couple minutes.


The screw turns 23 rpm.  We have considered changing to a 1200 rpm motor for the press, to reduce screw wear; a 900 rpm is not available.  They put on their ammeter for me.  Amps run 18 and 20, on 208 volt power, so we are not at all short of power or torque.


There was a heavy layer of sand in the bottom of the press liquor collection pan.  This must be coming from where the wedgewire screen has worn down to where the slots are quite wide near the discharge.  If it wears through or bursts, they will weld on a patch.


Intermittently you can hear rocks and pebbles going through the press.  These likely come from the road grit they wash off the trucks.


The cone rotates, but there is no real stripper pin on the inside face of the cone, just four bolt heads.  The cone opens about 2" and the cake comes out very well.


They have a TR Blossom (Kerry Doyle's old company in Abbotsford) drag flight draining conveyor.  It had a 6" squeezer screw at the discharge.  This did not work for them.


They found us on the internet.


We'd have a great business if all our customers were as smart and able as these people.