HTD10-40
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Better performance comes from working together. March 2015 Traction Control Using HTD10-40 Torque Divider Overview Controlling traction in propel applications can be a slippery problem. Parallel circuits can send all your flow to a spinning wheel. Series circuits can lead to wheel scuffing or damaging cavitation. Traditional solutions to this problem fall into two categories: inefficient and expensive. The inefficient solutions use an orificed leak path between the wheel motors to allow the outside motors additional flow when cornering. This solution can allow unwanted slippage when traveling on slick terrain. The expensive solutions involve sensors to determine when the flow needs of each wheel are different, valving to regulate the flow, and controllers to process the information. Not all applications can afford the added cost. Applications such as turf care machines are particularly sensitive to wheel scuffing. Ice surfacing machines are highly susceptible to slippage. And there are non-propel applications where torque must be evenly distributed between motors in series. 18 m 10 m Basic steering geometry: cornering vehicles must spin outside wheels faster. This 4-way 2-position valve halves the inlet pressure to balance torque between series motors in a drive circuit. Series Traditional Solutions Series Circuits We all know that oil in a hydraulic circuit follows the path of least resistance. In terms of traction control, this presents the need to equalize flow to multiple motors. Placing them in series is the easiest way to ensure they all receive the same flow. Flow in series circuit is equal, pressure is additive Series circuits have some limitations, however:Series the first being w/makeup that pressure is additive in a series circuit. The pressure available to the system must be shared by all motors in series. Motors in a series circuit must also be able to accommodate back pressure. For detailed information and specifications, visit www.hydraforce.com or contact your local HydraForce representative at www.hydraforce.com/distribs/world.htm HYDRAFORCE, INC. 500 Barclay Blvd. • Lincolnshire, IL 60069 USA Ph: 847 793 2300 • Fx: 847 793 0086 Web: www.hydraforce.com • E-Mail: sales@hydraforce.com St. Stephens Street • Birmingham B6 4RG England Ph: 44 121 333 1800 • Fx: 44 121 333 1810 Web: www.hydraforce.com • E-Mail: sales-uk@hydraforce.com ISO 9001 & QS 9000 • Member: National Fluid Power Association Member: British Fluid Power Association and Verband Deutscher Maschinen-und Anlagenbau e.V. (VDMA) ISO 9001 & ISO 14001 HYDRAFORCE HParallel YDRAULIC SYTEMS w/slip and CO., LTD. (CHANGZHOU)diff-lock 388 W. Huanghe Road • Building 15A GDH Changzhou Airport Indl Park Xinbei District • Changzhou, China 213022 Ph: 86 519 6988 1200 • Fx: 86 519 6988 1205 Web: www.hydraforce.com • E-Mail: sales@hydraforce.com ISO 9001: 2008 © 2014 HydraForce Inc. All rights reserved. HydraForce and the HydraForce logo are registered trademarks of HydraForce Inc. (bul_HTD10-40_03-2015)

Page 2 of 4 Parallel w/steering angle bypass The second limitation of series motor circuits is that flow through all motors is equal. Cornering vehicles need to spin the outside wheels faster than the inside ones. Failing to Series Parallel accommodate this fact leads to outside wheels scuffing the Series Series Parallel surface or worse, cavitating your motors. w/makeup Make-up Checks Make-up checks can alleviate cavitation, but all the pressure is dropped by the first motor. The downstream wheel provides no tractive effort: it’s just along for the ride. Series w/makeup Series w/makeup...

Controlled Pressure bar/psi Operation The HTD10-40 is a pressure reducing/relieving valve that adjusts its setting to half the pressure across 2 and 4. It allows flow from 3 to 4 or 2 to 3 as needed to balance the spool. The spool is balanced when pressure at 3 is half the pressure across 2 and 4. Supply Pressure bar/psi Application Applied between two series motors, the valve balances the pressure drop across each motor. This achieves efficient torque division regardless of differing motor speeds. The valve is sized to accommodate the flow difference between the two motors. Four Wheel...

Power Savings Comparing two systems: one with traditional flow dividers, one using HydraForce HTD10-40 torque dividers, we can show a power savings of 3.3 kW at full system flow (100 lpm). The system using torque dividers achieves traction control by dividing the pressure equally to all motors. Fluid only passes through the torque dividers when the wheels must turn at different speeds during cornering. Keeping all wheels at equal pressure ensures balanced torque without the losses and heat generation that flow controls exhibit. Flow Divider Circuit The traditional system achieves traction...