EZT® Integrated Zero-Turn Transaxle Service and Repair Manual (ZC & ZD Models) BLN-52622 July 2010
Table of Contents Section Page Foreword............................................................................................................................... 1 Description and Operation.................................................................................................. 2 Introduction................................................................................................................................................... 2 General Description.................................
foreword Headquartered in Sullivan, Illinois, Hydro-Gear® is a world leader in the design, manufacture, and service of quality hydrostatic transaxles for the lawn and garden industry. The mission of our company is to be recognized by our customers and the industry as a world-class supplier and the quality leader in everything we do. This Service and Repair Manual is designed to provide information useful in servicing and troubleshooting the Hydro-Gear EZT® Integrated Zero-Turn Transaxle.
Section 1. Description and Operation Introduction The purpose of this manual is to provide information useful in servicing the Hydro-Gear® Integrated Zero-Turn Transaxle (EZT®). This manual includes the EZT’s general descriptions, hydraulic schematics, technical specifications, servicing and troubleshooting procedures. The transaxle normally will not require servicing during the life of the vehicle in which it is installed.
EZT® HYDRAULIC FLOW SCHEMATIC Figure 2. Hydraulic Flow Illustration HYDRAULIC SCHEMATIC Figure 2 provides an illustration of the hydraulic oil circuit. The oil supply for the hydraulic system of the EZT® is also utilized for lubricating the components of the final drive assembly. The input shaft and pump cylinder block are turned in one direction only by the engine/ drive belt/pulley combination. Output of the oil flow is controlled by the direction and amount that the variable swashplate is angled.
EXTERNAL FEATURES EZT® AXLE SHAFT MAIN HOUSING BYPASS ARM FILL PORT INPUT SHAFT CONTROL ARM SIDE COVER BRAKE ARM COG BRAKE DISC FAN PULLEY AXLE SHAFT 4 EZT®
Technical Specifications Technical specifications for the EZT® are listed in Table 1. Table 1. Technical Specifications Input Speeds Weight of Unit Maximum: 3000 RPM Minimum: 1800 RPM 29 lbs. (13 Kg) Table 2.
Section 2. Safety This symbol points out important safety instructions which, if not followed, could endanger the personal safety and/or property of yourself and others. Read and follow all instructions in this manual before attempting maintenance on your transaxle. When you see this symbol - HEED ITS WARNING. Warning potential for serious injury Inattention to proper safety, operation, or maintenance procedures could result in personal injury, or damage to the equipment.
Section 3. Troubleshooting WARNING Do not attempt any servicing or adjustments with the engine running. Use extreme caution while inspecting the drive belt assembly and all vehicle linkage! Follow all safety procedures outlined in the vehicle owner’s manual. In many cases, problems with the EZT® are not related to a defective transaxle, but are caused by slipping drive belts, partially engaged bypass valves, and loose or damaged control linkages.
Section 4. Service and Maintenance NOTE: Any servicing dealer attempting a warranty repair must have prior approval before conducting maintenance of a Hydro-Gear® product unless the servicing dealer is a current Authorized Hydro-Gear Service Center. External Maintenance Regular external maintenance of the EZT® should include the following: Fluids The fluids used in Hydro-Gear products have been carefully selected, and only equivalent, or better products should be substituted.
FLUID CHANGE FLUID CHANGE PROCEDURE This transaxle is factory filled, sealed and does not require oil maintenance. However, in the event of oil contamination or degradation, oil addition or change may alleviate certain performance problems. 4. Position the transaxle so the oil will drain completely out of the housing. 1. Remove the transaxle from the vehicle. 6. Install the oil fill port fitting. NOTE: If removing the wheel from the transaxle, do so by removing the four (4) lug nuts.
PURGING PROCEDURES Due to the effects air has on efficiency in hydrostatic drive applications, it is critical that it is purged from the system. These purge procedures should be implemented any time a hydrostatic system has been opened to facilitate maintenance or any additional oil has been added to the system. Air creates inefficiency because its compression and expansion rate is higher than that of the oil approved for use in hydrostatic drive systems.
RETURN TO NEUTRAL SETTING Warning WARNING potential for serious injury Do not attempt any servicing or adjustments with the engine running. Use extreme caution while inspecting the drive belt assembly and all vehicle linkage! Inattention to proper safety, operation, or maintenance procedures could result in personal injury, or damage to the equipment. Before servicing or repairing the EZT®, fully read and understand the safety precautions described in this section.
Section 5. Repair HOW TO USE THIS MANUAL Each subassembly illustrated in this section is illustrated with an exploded view showing the parts involved. The item reference numbers in each illustration are for assembly instructions only. See page 31 for part names and descriptions. A complete exploded view and item list of the transaxle is provided at the end of the repair section. GENERAL INSTRUCTIONS Cleanliness is a primary means of assuring satisfactory life on repaired units.
TOOLS AND TORQUES Table 5. Required Tools Miscellaneous EZT® Service & Repair Manual Flat Blade Screw Driver (2) Torque Wrench Air Impact Wrench Rubber Mallet Breaker Bar Side Cutters/Snips Pliers Needle Nose Large External Snap Ring Small Internal Snap Ring Sockets 1/2”-3/8” Adapter 3/8” Deep 1/2” Deep 7/16” Deep 9/16” Deep 3/4” Deep 13/16” Deep 7/8” T-25 Torx Head T-40 Torx Head Apex AN-08 Table 6.
WHEEL HUB AND NUT (CODE - A, C, F, or H) Character 4 in the model number code = A, C, F, or H * * ** -**** - **** EXAMPLE: Z - H Refer to Figure 6. Disassembly Assembly NOTE: This procedure is only necessary if your unit is equipped with a pin locking nut (Figure 6a). Other units under this code are not equipped with a pin locking nut. NOTE: Anytime a hub and/or hub nut is removed, it must be replaced with a new hub and/or hub nut. 1. Place the axle so that the pin lock is at the 9 o’clock position.
WHEEL HUB AND NUT (CODE - P, R, T, or U) Character 4 in the model number code = P, R, T, or U * * ** -**** - **** EXAMPLE: Z - P Refer to Figure 7. Disassembly Assembly NOTE: The following procedure is used for teardown of the EZT unit when assembled with a taper lock shaft. The hub and hub nut should not be removed unless they have been damaged. NOTE: In a situation that a hub and/or hub nut is damaged and must be removed it must be replaced with a new hub and/or hub nut. 1.
CONTROL ARM AND BYPASS ARM Refer to Figure 8. Disassembly 1. Loosen and remove the lock nut (26) and flat washer (24). Discard the lock nut (26) and flat washer (24). 2. Remove the torx head screw (25) from the directional control. 3. Remove control arm (23) and pucks (22). Discard the pucks. 4. Remove the bypass arm retaining ring (18) and bypass arm (17). Discard the retaining ring. Assembly 1. Install the bypass arm (17) onto the bypass rod. Secure the bypass arm with a new retaining ring (18). 2.
SEAL KIT REPLACEMENT Before disassembly, wipe the unit free of any debris to avoid contamination. Refer to Figure 9. Input Seal 1. Remove the input pulley from the input shaft. 2. Remove the seal retaining ring (34). 3. Carefully pull the input seal (33) out of the housing bore with a “hook” type tool. Care must be taken to avoid damage to the housing bore or shaft sealing area. 4. Lubricate the new seal with petroleum jelly prior to installation. 5.
COG BRAKE ASSEMBLY Refer to Figure 10. 2. Check for excessive looseness at the arm pivot point. Disassembly 1. Remove the control arm and bypass arm. See page 16. 2. Remove the oil from the transaxle. See page 9. 3. Remove the brake arm spring (75), if installed. Remove the brake arm screw(s) (73), washer(s) (72), brake arm (74) and bushing(s) (71). 4. Remove the retaining ring (14) and cog brake disc (100). 5. Remove the motor shaft lip seal (10), if removing the side housing. Inspection 1.
DISC BRAKE ASSEMBLY Refer to Figure 11. 2. Check for excessive looseness at the arm pivot point. Disassembly Assembly 1. Remove the control arm and bypass arm. See page 16. 1. Install the motor shaft lip seal (10), if removed. Refer to page 17. Remember to use a seal protector during installation. 2. Remove the oil from the transaxle. See page 9. 2. Install the inner puck (150), rotor (100), outer puck (150) and puck plate (151). 3. Remove the brake arm bias spring (75). 4.
SIDE COVER Refer to figure 12. Inspection Disassembly 1. Inspect the bearing and bushing areas of the side cover. 1. Remove the control arm and bypass arm. See page 16. 2. Remove the oil from the transaxle. See page 9. 3. Remove the brake assembly. See pages 18 and 19. 4. Remove the motor shaft lip seal. See page 17. 5. Remove the side housing screws (9) and belt deflector (144), if installed. 6. Pull the side housing (68), leaving the axle (49) and bull gear (46) assembled in the main housing.
AXLE SHAFT, REDUCTION GEARS AND EXPANSION PLATE Refer to Figure 13. 3. Inspect the axle shaft, bearing and bushing. Disassembly 1. Remove the bypass arm and control arm. See page 16. 2. Remove oil from the transaxle. See page 9. 4. Inspect the expansion plate. Assembly 3. Remove the side cover. See page 20. 1. Apply a small bead of sealant to the expansion plate area of the housing. See page 29. Install the expansion plate (53). Torque the screws according to Table 6. 4.
MOTOR SHAFT Refer to Figure 14. Disassembly Assembly 1. Remove the control arm and bypass arm. See page 16. 1. Insert the motor shaft (39) with the pinnion gear (38) and flat washers (36 & 40) into the center section (57). 2. Drain the oil from the transaxle. See page 9. 2. Install the reduction gears. See page 21. 3. Remove the side cover. See page 20. 3. Install the side cover. Refer to page 20. 4. Remove the reduction gears. See page 21. 4. Install new seals. Refer to page 17. 5.
INPUT SHAFT AND BYPASS ROD Refer to Figure 15. Disassembly 1. Remove the control arm and bypass arm. See page 16. 2. Drain the oil from the transaxle. See page 9. installing the input shaft seal. 5. Deburr the end of the bypass rod. Install the bypass rod (15), retaining ring (14), seal (13) and retaining ring (16). 6. Install the motor shaft. See page 22. 7. Install the reduction gears. See page 21. 3. Remove the side cover. See page 20. 8. Install the side cover. See page 20. 4.
HYDRAULIC COMPONENTS Refer to Figures 16-25. Disassembly 1. Remove the bypass arm and control arm. See page 16. 2. Drain the oil from the transaxle. See page 9. 3. Remove the side cover. See page 20. 4. Remove the reduction gears. See page 21. 5. Remove the motor shaft. See page 22. 6. Remove the input shaft and bypass rod. See page 23. 7. (See Figure 16) Remove the swashplate (19) and pump cylinder block (4) as one assembly.
HYDRAULIC COMPONENTS 19. Reassemble the pistons, springs and thrust washers into the cylinder block and set aside. (Center Section/Filter) 3. (See Figure 22) Install the new filter base (61) onto the center section (57). Inspection 4. It will be necessary to clean the check plugs prior to re-assembly. Install the check plugs (56), in their correct location, into the center section (57). Tighten the check plugs according to Table 6. 20. Remove the thrust bearing assembly (35) from the housing (1).
(Swashplate/Pump Block) 11. (See Figure 19) Install the pump thrust bearing (35) in the trunnion machined swashplate (19). NOTE: Place the thin race of the bearing towards the swashplate. The thick race must face the pistons. 12. (See Figure 17) Place the pump block assembly (4), pistons down, on top of the thrust bearing in the swashplate (19). 13. Coat the pump running surface with clean motor oil. 14.
Figure 19. Figure 22. 1 Figure 20. 35 6 Figure 23. Figure 21.
TRANSAXLE INSTALLATION Use the following procedure to complete the installation of the transaxle on the vehicle. 1. Install and secure the transaxle on the vehicle according to the instructions in the vehicle owner’s manual. 6 19 57 1 39 2. With the vehicle raised, install the wheels on the axles, and snug the wheel hardware. 3. Lower the vehicle wheels to the ground and torque the wheel hardware per the vehicle owner’s manual. 4 38 Figure 24. Figure 25.
ASSEMBLY AFTER A COMPLETE TEARDOWN If the unit has been torn down completely, the following summary identifies the assembly procedures necessary to completely assemble the unit. Each assembly procedure is located by a page reference. 3. Install the axle shaft, reduction gears and expansion plate. See page 21. The part reference numbers provided in each assembly procedure are keyed to the individual exploded views, and are also keyed to the complete unit exploded view on page 30. 5.
SEALANT APPLICATION NOTE: Prior to applying the new sealant, the old sealant must be removed from all surfaces. A small consistent bead of the sealant around the housing face will be sufficient. Use sparingly. The illustration below indicates the correct areas.
Notes EZT® 31
32 73 71 72 74 119 120 121 160 73 70 OR 71 55 123 122 73 74 55 16X 9 159 74 72 73 72 71 OR 158 75 157 154 C 55 151 2X 150 10* 122 123 120 OR 121 54 144 153 100 68 73 2X 155 E AK 156 BR DIS 72 75 55 100 71 14* 2 121 122 71 74 3X 123 120 73 IT EK G AK RIN R B SP OR W/ IT E E K OL AK H H OR R B UG RO TH IT EK N AK PI BR EVIS CL IT EK T AK UN OR BR MO P TO 74 55 54 6X 131 3X 130 54 41 36 37* 45* 38 46 43 44 39 40 3X 12 42 47 2X 65
EZT® ITEMS List No. 1 DESCRIPTION No.
Glossary of Terms Axial Piston: Type of design for hydraulic motors and pumps in which the pistons are arranged parallel with the spindle (input or output shaft). Bantam Duty: A descriptive term relating to the product capacity (meaning: light duty). Bypass Valve: A valve whose primary function is to open a path for the fluid to bypass the motor or pump. Also referred to occasionally as the freewheel valve or dump valve.
Hydrostatic Transmission: The combination of a hydraulic pump and motor in one housing to form a device for the control and transfer of power. Inlet Line: A supply line to the pump. Integrated Zero-Turn Transaxle: The combination of a hydrostatic transmission and gear case in one housing to form a complete transaxle. Manifold: A conductor which provides multiple connection ports.
©2010 Hydro-Gear Printed in U.S.A. Rev.
