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NOV 28, 2025

How the AST Hydraulic and Electrical Systems Work

For fleets that depend on reliable loading operations, a dependable tuck under liftgate can mean the difference between uptime and downtime. The Anthony AST liftgate is engineered with a low-pressure hydraulic system and simplified electrical architecture designed for years of dependable service with minimal maintenance.

This article explores how the AST power system—its hydraulics, electrical controls, and built-in safety mechanisms—work together to ensure safe, consistent operation in daily fleet use. Where relevant, comparisons to the AST-L and AST-Plus models are provided, as these models share similar architecture but serve different bed height applications.

• Documentation Resources from Palfinger
• The Heart of the System: Hydraulic Configurations
• The Centralized Hydraulic System (CHS)
• Electrical Design and Safety Features
• Electrical Control Layout and Operator Function
• Hydraulic Maintenance and Fluid Requirements
• Safety Engineering Built Into Every AST
• Conclusion

Documentation Resources from Palfinger

Information in this article is sourced from Anthony AST manuals as well as our team’s expertise. Always refer to your specific liftgate’s manuals for complete procedures and serial number, model, and year-specific details.

Reference PDFs used:

• Anthony Liftgates Product Guide
• Anthony AST Brochure (2014)
• Anthony AST Operation Manual
• Anthony AST Installation Manual
• Anthony AST Parts Manual (L-101A-10-2018)

The Heart of the System: Hydraulic Configurations

Gravity-Down vs. Power-Down Operation

Anthony offers the AST liftgate in two main hydraulic configurations: gravity-down and power-down. Both use the same basic power pack design but differ in how the platform lowers.

• Gravity-Down System: The platform lowers by gravity as hydraulic pressure is released. The power unit energizes only during lifting, which minimizes energy consumption and simplifies service (Parts Manual, pp. 14, 22).
• Power-Down System: Adds an additional hydraulic valve and solenoid coil, allowing powered lowering under full control. This setup ensures consistent movement even under light or uneven loads (Parts Manual, p. 21).

Both configurations use an electric motor driving a hydraulic pump, with an integrated adjustable relief valve, flow control valve, and high-pressure hoses routed to a single lift cylinder.

Each power pack includes:

• A reservoir with breather and filler cap
• A 200 amp fused power cable
• A 10 amp in-line fuse for the control circuit
• Precision JIC and SAE hydraulic fittings for leak-free performance (Parts Manual, pp. 13–15)

Operating at low hydraulic pressures, the AST’s design reduces component wear and fluid stress, ensuring smoother and quieter motion (Product Guide, p. 17).

The Centralized Hydraulic System (CHS)

Stainless Steel Pump Box: Protection and Accessibility

A key design strength of the Anthony AST is its Centralized Hydraulic System (CHS) with a stainless steel pump box, which houses both electrical and hydraulic components. This sealed enclosure keeps out dirt, moisture, and debris, ensuring long service life for sensitive electronics (Brochure, p. 2).

Inside the pump box, technicians will find the hydraulic power unit assembly, control wiring harness, and a removable cover panel for maintenance access (Parts Manual, p. 12).

Advantages of the CHS:

• Weather protection: Stainless steel resists corrosion and protects components from road spray and salt.
• Cleaner installation: Preassembled units minimize field wiring.
• Service accessibility: Centralized design simplifies diagnostics and fluid service.

This system is shared across the AST family—AST-L uses a shorter mounting structure for lower beds, and AST-Plus includes additional hydraulic components for higher capacities (Installation Manual, p. 11).

Electrical Design and Safety Features

System Overview

The AST electrical system is compact and highly protected. A 200-amp main fuse is installed between the truck battery and motor, while a 10-amp in-line fuse inside the pump box protects the control switch circuit (Parts Manual, p. 17). These dual protections prevent overloads and short circuits.

Main electrical elements include:

• Motor start solenoid
• Power-up solenoid (and power-down solenoid on applicable models)
• Control switch assembly
• Optional cut-off solenoid or cab-mounted power switch (Installation Manual, pp. 24–25)

Grounding and Cable Routing

Proper grounding ensures current flows directly to the frame, not through sensitive vehicle systems. The Installation Manual warns that poor grounding can create dangerous current paths through brake or steering lines (p. 20).

Installers are instructed to:

• Attach a ground strap (same or larger gauge as the main power cable) from the pump box to the truck frame.
• Route cables using tie wraps or wire clips, avoiding sharp edges, heat, or fuel lines.
• Apply corrosion inhibitor to exposed terminals for long-term reliability.

Control Switch and Circuit Protection

The control system is designed for simplicity and operator safety. A heavy-duty marine-duty potted toggle switch controls all movement (Brochure, p. 2). This switch is sealed against moisture, preventing corrosion and maintaining reliable electrical contact in all weather conditions.

The switch connects through a control cable routed through a protective grommet in the dock bumper before entering the pump box (Installation Manual, p. 20). Each control circuit is individually fused to protect both the operator switch and solenoid coils.

Electrical Control Layout and Operator Function

Operator Interface

The AST’s control system is designed with the operator’s workflow and safety in mind. Located on the curbside post of the truck body, the control toggle is positioned for visibility and safe operation away from the platform edge (Installation Manual, p. 20). ç

Operators use a simple UP/DOWN toggle to control the hydraulic pump:

• UP energizes the motor start solenoid, pressurizing the cylinder to lift the platform.
• DOWN (gravity or power) opens the corresponding valve, allowing smooth lowering. For power-down models, an additional solenoid and hydraulic valve provide powered descent under full control (Parts Manual, pp. 21–22).

Anthony emphasizes using only the factory control switch for operation unless an approved remote or dual control option is installed (Brochure, p. 2).

Optional Power Cutoff Systems

For security and safety, Anthony offers optional electrical cut-off systems:

• Cab-Mounted Cutoff Switch: Installs near the driver’s seat to disable power when the truck is parked (Installation Manual, p. 24).
• Cutoff Solenoid Kit: Automatically interrupts the power cable between the fuse and the pump box; essential for tilt-cab vehicles where direct battery access is limited.

These features prevent unauthorized or accidental activation and are strongly recommended for all fleet installations.

Service-Friendly Wiring

Every AST liftgate includes labeled wiring and color-coded cables for simplified service and replacement (Parts Manual, p. 13). The control box wiring diagram identifies each circuit by color:

• White: Motor control
• Black: Fuse lead (10-amp)
• Green: Ground
• Red: Power-down circuit (where applicable)

Combined with centralized fusing, this design makes the AST’s power system one of the most straightforward and serviceable in the tuck under liftgate category.

Hydraulic Maintenance and Fluid Requirements

Approved Hydraulic Fluids

According to the Operation Manual (p. 12), Anthony specifies the following hydraulic fluids:

• Dexron VI Automatic Transmission Fluid (ATF)
• Dexron III ATF
• Hyken Glacial Blue Hydraulic Fluid

For cold weather, Hyken Glacial Blue is recommended due to its low-temperature viscosity. Mixing fluids is discouraged unless they are of the same type and standard.

Fluid Check and Replacement

• For gravity-down models, check fluid with the platform on the ground.
• For power-down models, check with the platform raised. In both cases, the oil should be within ½ inch of the reservoir top (Operation Manual, p. 12).

Anthony recommends replacing hydraulic fluid every 12–24 months, depending on duty cycle or contamination.

Filtration and Line Integrity

The power pack includes an internal screen filter and JIC 90° fittings on all pressure lines for leak prevention (Parts Manual, p. 13). These fittings maintain system pressure and prevent vibration-induced leaks that can cause slow or uneven lifting.

Safety Engineering Built Into Every AST

Anthony’s safety-first approach is evident in every part of the AST design. The mechanical safety latch acts as a redundant system to the hydraulic circuit, securing the platform during transit (Brochure, p. 2).

Key built-in safety systems include:

• Pressure-compensated flow valve to prevent “free-fall” under hydraulic failure (Brochure, p. 2)
• Spring-assist platform for controlled manual handling (Brochure, p. 2)
• Latch pin lock for mechanical restraint during transport (Installation Manual, p. 23)
• Warning decals at operating positions to ensure compliance and operator awareness (Operation Manual, p. 15)

This engineering focus—low pressure, controlled motion, and redundant safety—keeps operators and cargo protected under all working conditions.

Conclusion

The Anthony AST tuck under liftgate is a purpose-built, low-maintenance solution engineered for safety and reliability. Its stainless steel pump box, low-pressure hydraulics, and dual-fuse electrical protection combine into a clean, compact system that’s easy to operate and service.

For upfitters, the preassembled hydraulic system and clearly routed electrical harness simplify installation. For fleet operators, the weatherproof controls and factory-calibrated flow valves translate to years of dependable service.

When it’s time for replacement components, LiftGateMe provides genuine OEM liftgate parts designed specifically for the Anthony AST, AST-L, and AST-Plus models — ensuring every system maintains factory-grade performance and safety. Contact us and let us find the right solution for your specific liftgate.