Ernest Industries
Shortstop 3.5 Concrete Mixer Chassis Information
The Shortstop 3.5 mixer body requires a 25,900-26,000 lb (11,800 kg) GVW (gross vehicle weight chassis). GVW is maximum total weight of the chassis, mixer body, fuel, operator and concrete. Ultimately, the combined weight of the chassis & mixer body dictate the capacity rating of the mixer body. Most medium duty chassis will permit loading of 3.0 - 3.5 yards capacity of concrete.

A concrete mixer body is powered by a hydraulic pump that requires live (continuous) power. The mixer drum must continue turning whether the chassis is moving or stopped and/ or the chassis clutch is engaged or disengaged. The hydraulic pump is typically powered by the truck chassis and here are options for powering the Shortstop 3.5 Mixer.

FPTO (Front Engine PTO)
Front mounted engine PTO is the most common method of driving the hydraulic pump. The hydraulic pump is mounted on the front of the chassis and connected to the crankshaft of the engine with a drive shaft.

Many new chassis can be ordered with front hydraulic PTO provision. Some chassis (new & used) can be modified for FPTO, see attached information by make and model.

RPTO (Rear Transmission PTO)
Rear transmission PTO is a very nice drive system for concrete mixers, the hydraulic pump can be installed under the chassis out of harms way. The chassis must be equipped with an automatic transmission, Allison Model RDS 3000, RDS 3500 or RDS 4500. These transmissions are equipped with live PTO power which means the PTO continues to turn if the chassis is stopped or in neutral. Other transmissions can be equipped with PTO provisions but DO NOT feature the live hydraulic power option.

In addition to the transmission, a spur gear and hydraulic pump mounting brackets must be installed. Ernest part number OE3.5-18.

REPTO (Rear Engine PTO)
REPTO or rear engine PTO is a PTO drive powered directly from the chassis engine. Available only on UD 2600 cab forward chassis. The hydraulic pump is directly coupled to the REPTO shaft. The UD chassis must be special ordered with concrete mixer drive. Contact Ernest Industries for more information.

Auxiliary Engine Drive (Self Contained Auxiliary Power Source)
A self contained diesel engine is supplied to power the concrete mixer. The engine is typically installed in front of the mixer and requires a longer wheel base and minimum 30,000 lb (13,600 kg) chassis GVW. The auxiliary engine supplies power exclusively to the mixer enabling the mixer to be installed on most any chassis. The auxiliary engine typically draws fuel from the chassis tank(s) but is equipped with separate battery and charging system. See part number OE3.5-9.

Ernest part number OE3.5-9

Common Questions
  • Can I power the mixer with a manual transmission chassis equipped with PTO?
    • NO, each time the clutch is disengaged to shift gears or bring the chassis to a stop, the mixer drum will also stop.  In addition, most PTO drives on manual transmission are not designed to be operated at highway speeds.
  • Can I power the mixer with an automatic transmission that is equipped with a PTO port?  
    • Yes if the transmission is an Allison RDS 3000, RDS 3500 or RDS 4500.  If not, NO.  The PTO will stop when the chassis stops or is put in reverse.  In addition, these types of PTO drives are not designed to be operated at highway speeds.
  • Can I modify a new or used chassis for FPTO?
    • Yes & No depending on the specific chassis.  See the attached list for detailed information by make and model.  If you have specific questions, contact Ernest Industries.
Here is summary information on the most popular retrofits. If the chassis you are considering is not listed, contact Ernest Industries for more information.

  • 2003-2009 F650 & F750, must be ordered with RDS 3000, RDS 3500 automatic transmission. FPTO not possible, radiator sits too low.
  • 2000-2003 F650 & F750 is very easy to retrofit, install front frame extension, radiator is mounted with clearance for a drive shaft, Ernest part number OE3.5-17 budget $2,000 for retrofit.
  • 1999-1996 F650, retrofit radiator and add front frame extension. We have been unable to purchase a radiator from Ford, modifications to factory radiator completed by radiator shop. Budget $1,500- 2,500 for retrofit.
  • 1996 & later: No Experience
  • 2001-Current, model 4300-4400, known as (NGV) trucks.  Must be equipped Allison RDS 3000, RDS 3500 or RDS 4500 automatic transmission and RPTO drive. Unable to modify for FPTO radiator too low and factory does not offer a front PTO provision. 
  • 2001-Current 7300 Severe Service chassis (NGV) available from factory with FPTO.
  • 1990-2001 model 4700 & 4900, factory retrofitted with FPTO equipment including new radiator, new air/air exchanger.  These are great trucks to retrofit because all equipment is factory available.  International will charge approximately $5,500 to complete the factory retrofit.  In addition, add Ernest part number OE3.5-17.  Budget a total of $7,000 for retrofit
  • 2002- Current Top Kick Model C6500 and C7500 with either CAT or Duramax diesel engines only.  Easy to retrofit, requires front frame extension; see Ernest part number OE3.5-17.  Budget $1,500 for retrofit.
  • 2001- 1996 Top Kick C6500 or C7500 with Cat engine.  Requires front frame Extensions and modifications to A frame cross member.  See Ernest Industries Part number OE3.5-17.  Budget $2,000 for retrofit.
Isuzu/GM Cab Forward
  • GM T6500 or T7500, Isuzu F Series.  Must be equipped with Allison RDS  3000, RDS 3500 or RDS 4500 automatic transmission.  The chassis can be ordered from factory, a very difficult find in a used vehicle.  Add Ernest part number OE3.5-18 for RPTO brackets.  Budget $1,600 for retrofit.
  • 2000 - Current with Cat engine our only experience. Requires front frame extensions and replacement front bumper. Budget $2,000 for retrofit.
UD (Nissan)
  • UD 2600 cab forward chassis.  Must be equipped with factory installed REPTO specific to concrete mixers.  Contact Ernest Industries for more information.
Most used medium duty trucks (less than 26,000 lb GVW) trucks are equipped with either hydraulic disc or air brakes.  We recommend trucks with air brake systems because when discharging concrete all wheels are locked with the air brake system.  Unlike a hydraulic brake system, which typically features a driveline brake that locks the rear wheels.  Delivering ready mix concrete in hilly terrain air brakes are a must.  We have many mixers successfully operating with hydraulic brakes but operators should be prepared to chock wheels when discharging on uneven terrain.  Make sure the parking brake is in good working order. 

There are hydraulic parking brake retrofit kits available.  Visit for additional information.

The UD 2600 chassis offers an air operated parking brake system standard on the unit.  This is an excellent safety feature and to our knowledge available only on the UD chassis.

All commercial trucks are required to have an annual DOT inspection.  The inspection covers major working parts on the chassis such as clutch, transmission, lights, brakes, parking brake, suspension and more.  We recommend prior to purchasing a used chassis have the DOT inspection completed as part of the purchase agreement.  Any needed repairs can be identified and then negotiated with truck dealer prior to purchase.

Ernest Industries is not in the business of selling used truck chassis.  However, we offer for sale-complete mixers installed on used chassis.  We make a conscious effort to be sure the chassis is in good working order.  Each chassis will have a current DOT inspection along with a copy of dealer’s description of the chassis and related equipment.  Used chassis purchased directly from Ernest Industries or a recommend Ernest Industries chassis dealer are sold “AS IS” with no warranty expressed or implied.  The Ernest Industries Shortstop mixer body carries a one-year warranty against defective parts and workmanship.  The details of our warranty can be found in the “Terms of Sale Section” of our Web Site.