Hopper Hydraulic Lift System Malfunction

Affected vehicles (1)

Component / system

Defect

Alamo Group Inc. is recalling certain 2021-2022 Schwarze A9SE Monsoon (single engine) street sweepers. The open center valve manifold of the hopper hydraulic lift system allows hydraulic fluid to continue to flow into the lift system under certain conditions, which can result in the lift system continuing to rise after the operator has disengaged it.

Risk / consequence

An unexpectedly rising lift system can contact an overhead obstruction or cause debris to fall, increasing the risk of injury.

Remedy

Dealers will mount additional valves, free of charge. Owner notification letters were mailed on December 6, 2022. Owners may contact Alamo Group's customer service at 1-830-379-1480.

Chronology of events

1. Sep 13, 2022

   On September 13, 2022, Schwarze was conducting testing on the hydraulic lift system for the A9SE Monsoon (single engine) street sweeper. Through the course of this testing it was discovered that while the vehicle was stationary, if the hopper was lifted by the operator above the center-of-gravity or if the hopper was lifted while the vehicle is on an incline, the hopper would continue to lift to its maximum height even after the operator disengaged the lifting mechanism. From September 13, 2022 to September 22, 2022, Schwarze conducted a safety investigation to assess the failure mode, the failure rate, and potential causes. Schwarze tested the hydraulic system and determined there was continued flow of hydraulic fluid after the lift system was disengaged by the operator. Schwarze tested a completed A9SE Monsoon vehicle on the lot and observed identical issues with the unexpected or continued lifting of the hopper. Based on this testing, Schwarze determined the issue was not isolated to a single vehicle. Schwarze then tested the hopper hydraulic lift system on the twin engine model of the A9 Monsoon which has a closed valve manifold to regulate the hopper hydraulic lift system and discovered that there were no issues with the hopper continuing to lift after the lift system was disengaged by the operator. Schwarze compared the two hydraulic systems and determined the different open center valve manifold on the single engine A9SE Monsoon was the cause of the continued flow of hydraulic fluid into the hopper hydraulic lift system after the operator had disengaged the lift system. As of October 10, 2022, Alamo was aware of no warranty claims, no deaths, and no injuries related to this issue. Alamo has not received any customer complaints related to this issue. On October 10, 2022, Alamo decided to declare a voluntary safety recall to remedy this issue.

Notification schedule

Dealer notification

DEC 14, 2022 - NR

Owner notification

DEC 14, 2022 - NR