This article presents our first product. It is a simplified lift to transport goods between two floors in a trading company. It was commissioned at the beginning of 2012 and has proven its worth in daily operation since then.
It is used in a newly built warehouse of the company H. Lohmann Schiffs- und Industriebedarf e. K. After the foundation stone was laid in 1985, the trading company established itself in the shipping town of Haren (Ems) by fulfilling customer-specific procurement requests and managed to quickly acquire customers beyond the town limits. Meanwhile the company has also set up offices in Rotterdam and Münster.
Last year, another major investment was the inauguration of a new hall at their head office in Haren. In addition to commercial space, it also has a two-storey storage area. A hydraulic goods lift is used to transport goods between the two levels effortlessly and efficiently.
The goods lift in detail
General design and structure
This simplified goods lift is an indirectly driven lift functioning as a column lift. This means that the platform is not moved directly by hydraulic cylinders, but indirectly via a pulley drive system. A total of four wire ropes are connected on one side to the lifting platform and on the other side to the guide frame and are deflected by a pulley. The hydraulic cylinders move these pulleys and so cause the platform to move up or down.
The power required to lift a drum to the first floor level is generated by a 4 kW under-oil unit. The simple design and the fact that the electric motor runs dampened in the hydraulic oil contribute to trouble-free operation with a pleasant background noise level.
The platform of the goods lift has a floor area of approximately 2.5 square metres, which offers sufficient space even for larger loads (for comparison: a Euro pallet has a surface area of approximately one square metre).
Operation and control
The goods lift is controlled by a programmable logic controller (PLC). A surface-mounted control unit with three buttons and an emergency stop switch serve as the operator’s interface.
The current position of the platform is indicated by the light of the corresponding button being on permanently. A movement is indicated by the flashing light of the respective button. In spite of the closed lift shaft, this system keeps the operator informed at all times where the platform is currently located.
If the lift system malfunctions, the display in the main control cabinet provides the first valuable information. Clear indications such as the keywords 'emergency stop' or 'overload' facilitate investigating the cause and allow operations to be resumed without much delay.
Safety
To exclude any danger, the simplified goods lift is housed in a closed shaft and may only be operated by trained personnel. To prevent unauthorised access to the hazard area, the access doors of the lift shaft are electromechanically locked. They can only be opened when the platform is on the current floor or with a special key in an emergency.
Of course, the usual safety mechanisms of hydraulic lifts are also part of the standard equipment. Among others, line break valves, a pressure switch and a pressure relief valve can be mentioned here. The hydraulic power unit is equipped with a bypass to check these safety devices. They can be used to simulate a hose break in the drive train of the simplified goods lift.
Despite this safety equipment, transport people is not permitted with this configuration. This would require additional safety functions and redundant systems.
Reasons for goods lifts
The decision to invest in a goods lift was made in particular because of the favourable cost-benefit ratio. Purchasing a forklift truck would also have been a possible alternative.
A simplified goods lift has a number of advantages over a forklift:
- Low acquisition and maintenance costs
- Small footprint
- Very easy to use
- No risk of damage from bumping/crashing into gates, doors, shelves, ...
- No external training or testing to operate the system (keyword: forklift driver’s licence)
