New Heavy-Duty Features On Poclain Wheel Motors

Diesel Progress North American Edition, April, 2001

Mobile hydraulics manufacturer Poclain Hydraulics has introduced new heavy-duty features on its established MS range of modular, high-torque, slow-speed wheel motors.

The new features center on an innovative design heavy-duty bearing support system marketed by the French company under the name DYNA . DYNA gives the MS motors increased structural strength, allows more compact, shorter construction and facilitates the inclusion of a heavy-duty, wet multidisc braking system in the motors, Poclain reported.

The major rationale behind this new braking option is increasing travel speeds in off-highway mobile machinery, which are necessitating heavier-duty braking components. According to Poclain, traditional hydrostatic or drum brake solutions are rapidly becoming inadequate in many types of agricultural, materials handling and construction equipment. The self-contained design of the new brake minimizes component wear and fall-off in performance due to external contamination typical of traditional drum brake designs. In addition, the need to adjust and renew brake shoes and pads is eliminated, noted the company.

The three-function multidisc brake acts as a progressive service brake, a failsafe emergency brake and a parking brake. It is actuated and cooled automatically during normal operation using the vehicle's hydraulic transmission oil. The bearing support doubles the mechanical strength of a standard MS motor, Poclain said.

The brake is integrated into the heavy-duty bearing support to allow handling of the high radial and axial loads prevalent in larger vehicles and those with large diameter wheels or flotation tires. At the same time, the overall length of the motor assembly is reduced by 4 in., the company states.

On the MSl8 wheel motor, for example, the braking specifications include a service brake force of 10,320 lb.ft. at 1450 psi, a fail-safe emergency rating of 6265 lb.ft. and a parking brake force of 7370 lb.ft. The nominal displacement of the MS18 is 106.6 cu.in/rev, theoretical torque is 1412 lb.ft. at 1000 psi, maximum speed is 150 rpm and maximum pressure is 6500 psi.

The company's North American headquarters in Sturtevant, Wis., recently announced that the AGCO 8600 utilizes DYNA to enhance the braking performance of the agricultural sprayer. Even loaded with a 1200 gal. chemical tank, two front-mounted MS18 wheel motors with DYNA brakes provide effective stopping power to this row crop sprayer. The brakes are actuated by a VB brake valve adapted to utilize the AGCO foot pedal and linkage assembly. The MS35 standard rear wheel motors, along with the MS18 DYNA motors, are designed to handle vehicle weight and loading generated by the large diameter tires.

Each wheel motor on the AGCO 8600 is equipped with a speed sensor that feeds into the SmartDrive electronic traction control system. The system responds instantaneously to wheel slip by restricting flow to individual motors. Traction control is available in all vehicle modes of operation, and in any wheel motor speed range.

The SmartDrive computer from Poclain includes the traction control programming, as well as the Total Control System (TCS) for complete transmission control. The TCS interfaces with the 340 hp Cummins Quantum engine to match engine performance to that of the wheel motors and tandem drive pumps. It also synchronizes pump and motor displacement to provide smooth automatic motor speed shift.

Poclain claims a range of benefits for heavy-duty applications using the on-demand, high-performance mechanical braking and high endurance of MS motors with DYNA bearing supports. Low installation cost is achieved due to the 'plug-and-go,' no-adjustment design of the service and parking brake, while lifetime costs are reduced due to the brake's zero maintenance requirement -- the brake discs are dimensioned to last the life of the motor and so eliminate service parts replacement costs, company engineers explained.

Minimum component count, simple assembly and manageable component size are intended to promote high reliability. A tooled boss is designed to protect hose fitting connections, and the brake mechanism itself is protected against contamination. In addition, MS motors with the DYNA bearing support and multidisc brake are available as complete braking systems including Poclain's VB series brake valves, pedal assemblies and accumulator charging valves.

The MS motor with DYNA bearing support is the first new product to be tested and qualified on the new vehicle proving grounds, commissioned last year at its Verberie headquarters. A high level of operational safety with enduring, consistent, on-demand braking power was attained, both on the test area and during rigorous bench testing, the company stated.