A system, comprising: a vehicle having a main engine and a hydraulic load; a service pack mounted in the vehicle, comprising: an engine, separate from the main engine, having an operating speed ranging from a low speed to a high speed; a hydraulic pump coupled to the engine, wherein the hydraulic pump is configured to receive hydraulic fluid from a hydraulic reservoir to supply a hydraulic output to the hydraulic load; characterised by a control system configured to control the hydraulic output, wherein the control system comprises a fine control mode configured to lock the engine in the low speed and control the hydraulic output in proportion to a percentage of a trigger activation; a hydraulic inlet valve disposed between the hydraulic reservoir and the hydraulic pump, and a hydraulic outlet valve disposed between the hydraulic pump and the hydraulic output, wherein both, the hydraulic inlet valve and the hydraulic outlet valve, are in communication with the control system and configured to vary the flow rate and/or the pressure of the hydraulic fluid entering in and/or leaving the hydraulic pump so as to vary the hydraulic output in the fine control mode. a vehicle having a main engine and a hydraulic load; a service pack mounted in the vehicle, comprising: an engine, separate from the main engine, having an operating speed ranging from a low speed to a high speed; a hydraulic pump coupled to the engine, wherein the hydraulic pump is configured to receive hydraulic fluid from a hydraulic reservoir to supply a hydraulic output to the hydraulic load; characterised by a control system configured to control the hydraulic output, wherein the control system comprises a fine control mode configured to lock the engine in the low speed and control the hydraulic output in proportion to a percentage of a trigger activation; a hydraulic inlet valve disposed between the hydraulic reservoir and the hydraulic pump, and a hydraulic outlet valve disposed between the hydraulic pump and the hydraulic output, wherein both, the hydraulic inlet valve and the hydraulic outlet valve, are in communication with the control system and configured to vary the flow rate and/or the pressure of the hydraulic fluid entering in and/or leaving the hydraulic pump so as to vary the hydraulic output in the fine control mode. an engine, separate from the main engine, having an operating speed ranging from a low speed to a high speed; a hydraulic pump coupled to the engine, wherein the hydraulic pump is configured to receive hydraulic fluid from a hydraulic reservoir to supply a hydraulic output to the hydraulic load; characterised by a control system configured to control the hydraulic output, wherein the control system comprises a fine control mode configured to lock the engine in the low speed and control the hydraulic output in proportion to a percentage of a trigger activation; a hydraulic inlet valve disposed between the hydraulic reservoir and the hydraulic pump, and a hydraulic outlet valve disposed between the hydraulic pump and the hydraulic output, wherein both, the hydraulic inlet valve and the hydraulic outlet valve, are in communication with the control system and configured to vary the flow rate and/or the pressure of the hydraulic fluid entering in and/or leaving the hydraulic pump so as to vary the hydraulic output in the fine control mode.